diff --git a/app/server/lib/DocApi.ts b/app/server/lib/DocApi.ts
index be9c1028..40c788d6 100644
--- a/app/server/lib/DocApi.ts
+++ b/app/server/lib/DocApi.ts
@@ -639,7 +639,7 @@ async function handleSandboxError<T>(tableId: string, colNames: string[], p: Pro
       if (match) {
         throw new ApiError(`Invalid row id ${match[1]}`, 400);
       }
-      match = e.message.match(/\[Sandbox\] KeyError '(.*?)'/);
+      match = e.message.match(/\[Sandbox\] KeyError u?'(.*?)'/);
       if (match) {
         if (match[1] === tableId) {
           throw new ApiError(`Table not found "${tableId}"`, 404);
diff --git a/app/server/lib/NSandbox.ts b/app/server/lib/NSandbox.ts
index b97c4cf7..4d06b112 100644
--- a/app/server/lib/NSandbox.ts
+++ b/app/server/lib/NSandbox.ts
@@ -78,7 +78,7 @@ export class NSandbox implements ISandbox {
   public readonly childProc: ChildProcess;
   private _logTimes: boolean;
   private _exportedFunctions: {[name: string]: SandboxMethod};
-  private _marshaller = new marshal.Marshaller({stringToBuffer: true, version: 2});
+  private _marshaller = new marshal.Marshaller({stringToBuffer: false, version: 2});
   private _unmarshaller = new marshal.Unmarshaller({ bufferToString: false });
 
   // Members used for reading from the sandbox process.
diff --git a/sandbox/grist/acl.py b/sandbox/grist/acl.py
index f16064da..c73b4161 100644
--- a/sandbox/grist/acl.py
+++ b/sandbox/grist/acl.py
@@ -109,8 +109,7 @@ def prepare_acl_col_renames(docmodel, useractions, col_renames_dict):
   # Go through again checking if anything in ACL formulas is affected by the rename.
   for rule_rec in docmodel.aclRules.all:
     if rule_rec.aclFormula:
-      # Positions are obtained from unicode version of formulas, so that's what we must patch
-      formula = rule_rec.aclFormula.decode('utf8')
+      formula = rule_rec.aclFormula
       patches = []
 
       for entity in parse_acl_grist_entities(rule_rec.aclFormula):
@@ -129,7 +128,7 @@ def prepare_acl_col_renames(docmodel, useractions, col_renames_dict):
         patches.append(patch)
 
       replacer = textbuilder.Replacer(textbuilder.Text(formula), patches)
-      txt = replacer.get_text().encode('utf8')
+      txt = replacer.get_text()
       rule_updates.append((rule_rec, {'aclFormula': txt,
                                       'aclFormulaParsed': parse_acl_formula_json(txt)}))
 
diff --git a/sandbox/grist/acl_formula.py b/sandbox/grist/acl_formula.py
index 2d3ad887..17d2bc84 100644
--- a/sandbox/grist/acl_formula.py
+++ b/sandbox/grist/acl_formula.py
@@ -5,6 +5,8 @@ import tokenize
 from collections import namedtuple
 
 import asttokens
+import six
+
 
 def parse_acl_formula(acl_formula):
   """
@@ -26,10 +28,12 @@ def parse_acl_formula(acl_formula):
     Attr                    node, attr_name
     Comment                 node, comment
   """
+  if isinstance(acl_formula, six.binary_type):
+    acl_formula = acl_formula.decode('utf8')
   try:
     tree = ast.parse(acl_formula, mode='eval')
     result = _TreeConverter().visit(tree)
-    for part in tokenize.generate_tokens(io.StringIO(acl_formula.decode('utf-8')).readline):
+    for part in tokenize.generate_tokens(io.StringIO(acl_formula).readline):
       if part[0] == tokenize.COMMENT and part[1].startswith('#'):
         result = ['Comment', result, part[1][1:].strip()]
         break
diff --git a/sandbox/grist/actions.py b/sandbox/grist/actions.py
index ab932862..5ad7115a 100644
--- a/sandbox/grist/actions.py
+++ b/sandbox/grist/actions.py
@@ -116,7 +116,7 @@ def action_from_repr(doc_action):
   try:
     return decode_objects(action_type(*doc_action[1:]))
   except TypeError as e:
-    raise TypeError("%s: %s" % (doc_action[0], e.message))
+    raise TypeError("%s: %s" % (doc_action[0], str(e)))
 
 
 def convert_recursive_helper(converter, data):
diff --git a/sandbox/grist/autocomplete_context.py b/sandbox/grist/autocomplete_context.py
index fce1c102..f6c3c3b8 100644
--- a/sandbox/grist/autocomplete_context.py
+++ b/sandbox/grist/autocomplete_context.py
@@ -70,6 +70,9 @@ class AutocompleteContext(object):
     return self._context
 
   def process_result(self, result):
+    # 'for' suggests the autocompletion 'for ' in python 3
+    result = result.rstrip()
+
     # Callables are returned by rlcompleter with a trailing "(".
     if result.endswith('('):
       funcname = result[0:-1]
diff --git a/sandbox/grist/codebuilder.py b/sandbox/grist/codebuilder.py
index e969db84..a58f5865 100644
--- a/sandbox/grist/codebuilder.py
+++ b/sandbox/grist/codebuilder.py
@@ -118,9 +118,10 @@ def _create_syntax_error_code(builder, input_text, err):
   output_offset = output_ln.line_to_offset(err.lineno, err.offset - 1 if err.offset else 0)
   input_offset = builder.map_back_offset(output_offset)
   line, col = input_ln.offset_to_line(input_offset)
-  return "%s\nraise %s('%s on line %d col %d')" % (
+  message = '%s on line %d col %d' % (err.args[0], line, col + 1)
+  return "%s\nraise %s(%r)" % (
     textbuilder.line_start_re.sub('# ', input_text.rstrip()),
-    type(err).__name__, err.args[0], line, col + 1)
+    type(err).__name__, message)
 
 #----------------------------------------------------------------------
 
diff --git a/sandbox/grist/column.py b/sandbox/grist/column.py
index f0154a5c..7cbc8225 100644
--- a/sandbox/grist/column.py
+++ b/sandbox/grist/column.py
@@ -268,11 +268,43 @@ class DateTimeColumn(NumericColumn):
   def sample_value(self):
     return _sample_datetime
 
+
+class MixedTypesKey(object):
+  """
+  Sort key that can contain different types.
+  This mimics Python 2 where values of different types can be compared,
+  falling back on some comparison of the types when the values
+  can't be compared normally.
+  """
+
+  __slots__ = ("value",)
+
+  def __init__(self, value):
+    self.value = value
+
+  def __repr__(self):
+    return "MixedTypesKey({self.value!r})".format(self=self)
+
+  def __eq__(self, other):
+    return self.value == other.value
+
+  def __lt__(self, other):
+    try:
+      return self.value < other.value
+    except TypeError:
+      return type(self.value).__name__ < type(other.value).__name__
+
+
+if six.PY2:
+  def MixedTypesKey(x):
+    return x
+
+
 class PositionColumn(NumericColumn):
   def __init__(self, table, col_id, col_info):
     super(PositionColumn, self).__init__(table, col_id, col_info)
     # This is a list of row_ids, ordered by the position.
-    self._sorted_rows = SortedListWithKey(key=self.raw_get)
+    self._sorted_rows = SortedListWithKey(key=lambda x: MixedTypesKey(self.raw_get(x)))
 
   def set(self, row_id, value):
     self._sorted_rows.discard(row_id)
@@ -282,7 +314,8 @@ class PositionColumn(NumericColumn):
 
   def copy_from_column(self, other_column):
     super(PositionColumn, self).copy_from_column(other_column)
-    self._sorted_rows = SortedListWithKey(other_column._sorted_rows[:], key=self.raw_get)
+    self._sorted_rows = SortedListWithKey(other_column._sorted_rows[:],
+                                          key=lambda x: MixedTypesKey(self.raw_get(x)))
 
   def prepare_new_values(self, values, ignore_data=False, action_summary=None):
     # This does the work of adjusting positions and relabeling existing rows with new position
@@ -290,9 +323,11 @@ class PositionColumn(NumericColumn):
     # used for updating a position for an existing row: we'll find a new value for it; later when
     # this value is set, the old position will be removed and the new one added.
     if ignore_data:
-      rows = SortedListWithKey([], key=self.raw_get)
+      rows = []
     else:
       rows = self._sorted_rows
+    # prepare_inserts expects floats as keys, not MixedTypesKeys
+    rows = SortedListWithKey(rows, key=self.raw_get)
     adjustments, new_values = relabeling.prepare_inserts(rows, values)
     return new_values, [(self._sorted_rows[i], pos) for (i, pos) in adjustments]
 
diff --git a/sandbox/grist/depend.py b/sandbox/grist/depend.py
index 2408a4b0..d57a7829 100644
--- a/sandbox/grist/depend.py
+++ b/sandbox/grist/depend.py
@@ -77,9 +77,9 @@ class Graph(object):
     """
     Print out the graph to stdout, for debugging.
     """
-    print "Dependency graph (%d edges):" % len(self._all_edges)
+    print("Dependency graph (%d edges):" % len(self._all_edges))
     for edge in sorted(self._all_edges):
-      print "  %s" % (edge,)
+      print("  %s" % (edge,))
 
   def add_edge(self, out_node, in_node, relation):
     """
diff --git a/sandbox/grist/engine.py b/sandbox/grist/engine.py
index 3010a0c5..bf8ee3d0 100644
--- a/sandbox/grist/engine.py
+++ b/sandbox/grist/engine.py
@@ -34,12 +34,13 @@ import table as table_module
 import useractions
 import column
 import repl
+import urllib_patch  # noqa imported for side effect
 
 log = logger.Logger(__name__, logger.INFO)
 
 if six.PY2:
   reload(sys)
-  sys.setdefaultencoding('utf8')
+  sys.setdefaultencoding('utf8')  # noqa
 
 
 class OrderError(Exception):
@@ -1125,8 +1126,14 @@ class Engine(object):
       except Exception:
         log.error("Inconsistent schema after revert on failure: %s" % traceback.format_exc())
 
-      # Re-raise the original exception (simple `raise` wouldn't do if undo also fails above).
-      raise exc_info[0], exc_info[1], exc_info[2]
+      # Re-raise the original exception
+      # In Python 2, 'raise' raises the most recent exception,
+      # which may come from the try/except just above
+      # Python 3 keeps track of nested exceptions better
+      if six.PY2:
+        six.reraise(*exc_info)
+      else:
+        raise
 
     # Note that recalculations and auto-removals get included after processing all useractions.
     self._bring_all_up_to_date()
@@ -1183,8 +1190,15 @@ class Engine(object):
           self.rebuild_usercode()
         except Exception:
           log.error("Error rebuilding usercode after restoring schema: %s" % traceback.format_exc())
-      # Re-raise the original exception (simple `raise` wouldn't do if rebuild also fails above).
-      raise exc_info[0], exc_info[1], exc_info[2]
+
+      # Re-raise the original exception
+      # In Python 2, 'raise' raises the most recent exception,
+      # which may come from the try/except just above
+      # Python 3 keeps track of nested exceptions better
+      if six.PY2:
+        six.reraise(*exc_info)
+      else:
+        raise
 
     # If any columns got deleted, destroy them to clear _back_references in other tables, and to
     # force errors if anything still uses them. Also clear them from calc actions if needed.
diff --git a/sandbox/grist/functions/lookup.py b/sandbox/grist/functions/lookup.py
index 76492d02..a2c44bc3 100644
--- a/sandbox/grist/functions/lookup.py
+++ b/sandbox/grist/functions/lookup.py
@@ -93,15 +93,15 @@ def SELF_HYPERLINK(label=None, page=None, **kwargs):
   we might want to create links with `SELF_HYPERLINK(LinkKey_Code=$Code)`.
 
   >>> SELF_HYPERLINK()
-  'https://docs.getgrist.com/sbaltsirg/Example'
+  u'https://docs.getgrist.com/sbaltsirg/Example'
   >>> SELF_HYPERLINK(label='doc')
-  'doc https://docs.getgrist.com/sbaltsirg/Example'
+  u'doc https://docs.getgrist.com/sbaltsirg/Example'
   >>> SELF_HYPERLINK(page=2)
-  'https://docs.getgrist.com/sbaltsirg/Example/p/2'
+  u'https://docs.getgrist.com/sbaltsirg/Example/p/2'
   >>> SELF_HYPERLINK(LinkKey_Code='X1234')
-  'https://docs.getgrist.com/sbaltsirg/Example?Code_=X1234'
+  u'https://docs.getgrist.com/sbaltsirg/Example?Code_=X1234'
   >>> SELF_HYPERLINK(label='order', page=3, LinkKey_Code='X1234', LinkKey_Name='Bi Ngo')
-  'order https://docs.getgrist.com/sbaltsirg/Example/p/3?Code_=X1234&Name_=Bi+Ngo'
+  u'order https://docs.getgrist.com/sbaltsirg/Example/p/3?Code_=X1234&Name_=Bi+Ngo'
   >>> SELF_HYPERLINK(Linky_Link='Link')
   Traceback (most recent call last):
   ...
@@ -110,6 +110,7 @@ def SELF_HYPERLINK(label=None, page=None, **kwargs):
   txt = os.environ.get('DOC_URL')
   if not txt:
     return None
+  txt = six.text_type(txt)
   if page:
     txt += "/p/{}".format(page)
   if kwargs:
@@ -124,7 +125,7 @@ def SELF_HYPERLINK(label=None, page=None, **kwargs):
     parts[4] = urllib_parse.urlencode(query)
     txt = urllib_parse.urlunparse(parts)
   if label:
-    txt = "{} {}".format(label, txt)
+    txt = u"{} {}".format(label, txt)
   return txt
 
 def VLOOKUP(table, **field_value_pairs):
diff --git a/sandbox/grist/functions/text.py b/sandbox/grist/functions/text.py
index ffdc6838..35c588ac 100644
--- a/sandbox/grist/functions/text.py
+++ b/sandbox/grist/functions/text.py
@@ -1,16 +1,17 @@
 # -*- coding: UTF-8 -*-
 
 import datetime
-import dateutil.parser
 import numbers
 import re
 
+import dateutil.parser
 import six
 from six import unichr
 from six.moves import xrange
 
+from usertypes import AltText  # pylint: disable=import-error
 from .unimplemented import unimplemented
-from usertypes import AltText   # pylint: disable=import-error
+
 
 def CHAR(table_number):
   """
@@ -26,7 +27,7 @@ def CHAR(table_number):
 
 
 # See http://stackoverflow.com/a/93029/328565
-_control_chars = ''.join(map(unichr, range(0,32) + range(127,160)))
+_control_chars = ''.join(map(unichr, list(xrange(0,32)) + list(xrange(127,160))))
 _control_char_re = re.compile('[%s]' % re.escape(_control_chars))
 
 def CLEAN(text):
@@ -58,7 +59,7 @@ def CODE(string):
 
 
 def CONCATENATE(string, *more_strings):
-  """
+  u"""
   Joins together any number of text strings into one string. Also available under the name
   `CONCAT`. Similar to the Python expression `"".join(array_of_strings)`.
 
@@ -70,11 +71,15 @@ def CONCATENATE(string, *more_strings):
   u'abc'
   >>> CONCATENATE(0, "abc")
   u'0abc'
-  >>> CONCATENATE(2, " crème ", "brûlée".decode('utf8')) == "2 crème brûlée".decode('utf8')
-  True
+  >>> assert CONCATENATE(2, u" crème ", u"brûlée") == u'2 crème brûlée'
+  >>> assert CONCATENATE(2,  " crème ", u"brûlée") == u'2 crème brûlée'
+  >>> assert CONCATENATE(2,  " crème ",  "brûlée") == u'2 crème brûlée'
   """
-  return u''.join(val if isinstance(val, unicode) else str(val).decode('utf8')
-      for val in (string,) + more_strings)
+  return u''.join(
+    val.decode('utf8') if isinstance(val, six.binary_type) else
+    six.text_type(val)
+    for val in (string,) + more_strings
+  )
 
 
 def CONCAT(string, *more_strings):
@@ -90,8 +95,7 @@ def CONCAT(string, *more_strings):
   u'abc'
   >>> CONCAT(0, "abc")
   u'0abc'
-  >>> CONCAT(2, " crème ", "brûlée".decode('utf8')) == "2 crème brûlée".decode('utf8')
-  True
+  >>> assert CONCAT(2, u" crème ", u"brûlée") == u'2 crème brûlée'
   """
   return CONCATENATE(string, *more_strings)
 
@@ -443,48 +447,57 @@ def SUBSTITUTE(text, old_text, new_text, instance_num=None):
   Same as `text.replace(old_text, new_text)` when instance_num is omitted.
 
   >>> SUBSTITUTE("Sales Data", "Sales", "Cost")
-  'Cost Data'
+  u'Cost Data'
   >>> SUBSTITUTE("Quarter 1, 2008", "1", "2", 1)
-  'Quarter 2, 2008'
+  u'Quarter 2, 2008'
   >>> SUBSTITUTE("Quarter 1, 2011", "1", "2", 3)
-  'Quarter 1, 2012'
+  u'Quarter 1, 2012'
 
   More tests:
   >>> SUBSTITUTE("Hello world", "", "-")
-  'Hello world'
+  u'Hello world'
   >>> SUBSTITUTE("Hello world", " ", "-")
-  'Hello-world'
+  u'Hello-world'
   >>> SUBSTITUTE("Hello world", " ", 12.1)
-  'Hello12.1world'
+  u'Hello12.1world'
   >>> SUBSTITUTE(u"Hello world", u" ", 12.1)
   u'Hello12.1world'
   >>> SUBSTITUTE("Hello world", "world", "")
-  'Hello '
+  u'Hello '
   >>> SUBSTITUTE("Hello", "world", "")
-  'Hello'
+  u'Hello'
 
   Overlapping matches are all counted when looking for instance_num.
   >>> SUBSTITUTE('abababab', 'abab', 'xxxx')
-  'xxxxxxxx'
+  u'xxxxxxxx'
   >>> SUBSTITUTE('abababab', 'abab', 'xxxx', 1)
-  'xxxxabab'
+  u'xxxxabab'
   >>> SUBSTITUTE('abababab', 'abab', 'xxxx', 2)
-  'abxxxxab'
+  u'abxxxxab'
   >>> SUBSTITUTE('abababab', 'abab', 'xxxx', 3)
-  'ababxxxx'
+  u'ababxxxx'
   >>> SUBSTITUTE('abababab', 'abab', 'xxxx', 4)
-  'abababab'
+  u'abababab'
   >>> SUBSTITUTE('abababab', 'abab', 'xxxx', 0)
   Traceback (most recent call last):
   ...
   ValueError: instance_num invalid
-  """
+  >>> SUBSTITUTE( "crème",  "è", "e")
+  u'creme'
+  >>> SUBSTITUTE(u"crème", u"è", "e")
+  u'creme'
+  >>> SUBSTITUTE(u"crème",  "è", "e")
+  u'creme'
+  >>> SUBSTITUTE( "crème", u"è", "e")
+  u'creme'
+  """
+  text = six.text_type(text)
+  old_text = six.text_type(old_text)
+  new_text = six.text_type(new_text)
+
   if not old_text:
     return text
 
-  if not isinstance(new_text, six.string_types):
-    new_text = str(new_text)
-
   if instance_num is None:
     return text.replace(old_text, new_text)
 
@@ -505,22 +518,23 @@ def T(value):
   Returns value if value is text, or the empty string when value is not text.
 
   >>> T('Text')
-  'Text'
+  u'Text'
   >>> T(826)
-  ''
+  u''
   >>> T('826')
-  '826'
+  u'826'
   >>> T(False)
-  ''
+  u''
   >>> T('100 points')
-  '100 points'
+  u'100 points'
   >>> T(AltText('Text'))
-  'Text'
+  u'Text'
   >>> T(float('nan'))
-  ''
+  u''
   """
-  return (value if isinstance(value, basestring) else
-          str(value) if isinstance(value, AltText) else "")
+  return (value.decode('utf8') if isinstance(value, six.binary_type) else
+          value if isinstance(value, six.text_type) else
+          six.text_type(value) if isinstance(value, AltText) else u"")
 
 
 @unimplemented
@@ -565,8 +579,7 @@ def VALUE(text):
 
   >>> VALUE("$1,000")
   1000
-  >>> VALUE("16:48:00") - VALUE("12:00:00")
-  datetime.timedelta(0, 17280)
+  >>> assert VALUE("16:48:00") - VALUE("12:00:00") == datetime.timedelta(0, 17280)
   >>> VALUE("01/01/2012")
   datetime.datetime(2012, 1, 1, 0, 0)
   >>> VALUE("")
diff --git a/sandbox/grist/main.py b/sandbox/grist/main.py
index 3be8007a..7ffdf2f3 100644
--- a/sandbox/grist/main.py
+++ b/sandbox/grist/main.py
@@ -36,6 +36,7 @@ def table_data_from_db(table_name, table_data_repr):
   if table_data_repr is None:
     return actions.TableData(table_name, [], {})
   table_data_parsed = marshal.loads(table_data_repr)
+  table_data_parsed = {key.decode("utf8"): value for key, value in table_data_parsed.items()}
   id_col = table_data_parsed.pop("id")
   return actions.TableData(table_name, id_col,
                            actions.decode_bulk_values(table_data_parsed, _decode_db_value))
@@ -44,14 +45,8 @@ def _decode_db_value(value):
   # Decode database values received from SQLite's allMarshal() call. These are encoded by
   # marshalling certain types and storing as BLOBs (received in Python as binary strings, as
   # opposed to text which is received as unicode). See also encodeValue() in DocStorage.js
-
-  # TODO For the moment, the sandbox uses binary strings throughout (with text in utf8 encoding).
-  # We should switch to representing text with unicode instead. This requires care, at least in
-  # fixing various occurrences of str() in our code, which may fail and which return wrong type.
   t = type(value)
-  if t == unicode:
-    return value.encode('utf8')
-  elif t == str:
+  if t == six.binary_type:
     return objtypes.decode_object(marshal.loads(value))
   else:
     return value
diff --git a/sandbox/grist/migrations.py b/sandbox/grist/migrations.py
index 18d6bbc7..16bea4b2 100644
--- a/sandbox/grist/migrations.py
+++ b/sandbox/grist/migrations.py
@@ -73,7 +73,8 @@ def create_migrations(all_tables, metadata_only=False):
         new_col_info = {c['id']: c for c in new_schema[table_id].columns}
       # Use an incomplete default for unknown (i.e. deprecated) columns; some uses of the column
       # would be invalid, such as adding a new record with missing values.
-      col_info = sorted([new_col_info.get(col_id, {'id': col_id}) for col_id in data.columns])
+      col_info = sorted([new_col_info.get(col_id, {'id': col_id}) for col_id in data.columns],
+                        key=lambda c: list(six.iteritems(c)))
       tdset.apply_doc_action(actions.AddTable(table_id, col_info))
 
     # And load in the original data, interpreting the TableData object as BulkAddRecord action.
@@ -177,7 +178,7 @@ def migration1(tdset):
   if rows:
     values = {'tableRef': [r[0] for r in rows],
               'viewRef':  [r[1] for r in rows]}
-    row_ids = range(1, len(rows) + 1)
+    row_ids = list(xrange(1, len(rows) + 1))
     doc_actions.append(actions.ReplaceTableData('_grist_TabItems', row_ids, values))
 
   return tdset.apply_doc_actions(doc_actions)
@@ -212,14 +213,14 @@ def migration2(tdset):
     return actions.BulkUpdateRecord('_grist_Tables', row_ids, values)
 
   def create_tab_bar_action(views_to_table):
-    row_ids = range(1, len(views_to_table) + 1)
+    row_ids = list(xrange(1, len(views_to_table) + 1))
     return actions.ReplaceTableData('_grist_TabBar', row_ids, {
       'viewRef': sorted(views_to_table.keys())
     })
 
   def create_table_views_action(views_to_table, primary_views):
     related_views = sorted(set(views_to_table.keys()) - set(primary_views.values()))
-    row_ids = range(1, len(related_views) + 1)
+    row_ids = list(xrange(1, len(related_views) + 1))
     return actions.ReplaceTableData('_grist_TableViews', row_ids, {
       'tableRef': [views_to_table[v] for v in related_views],
       'viewRef':  related_views,
@@ -757,7 +758,7 @@ def migration20(tdset):
     # the name of primary view's is the same as the tableId
     return (view.name, -1)
   views.sort(key=view_key)
-  row_ids = range(1, len(views) + 1)
+  row_ids = list(xrange(1, len(views) + 1))
   return tdset.apply_doc_actions([
     actions.AddTable('_grist_Pages', [
       schema.make_column('viewRef', 'Ref:_grist_Views'),
diff --git a/sandbox/grist/moment.py b/sandbox/grist/moment.py
index 3e57d15b..b3fcf8f7 100644
--- a/sandbox/grist/moment.py
+++ b/sandbox/grist/moment.py
@@ -142,8 +142,9 @@ class TzInfo(_tzinfo):
   def tzname(self, dt):
     """Implementation of tzinfo.tzname interface."""
     abbr = self.zone.dt_tzname(dt, self._favor_offset)
-    # tzname must return a string, not unicode.
-    return abbr.encode('utf8') if isinstance(abbr, unicode) else abbr
+    if six.PY2 and isinstance(abbr, six.text_type):
+      abbr = abbr.encode('utf8')
+    return abbr
 
   def dst(self, dt):
     """Implementation of tzinfo.dst interface."""
diff --git a/sandbox/grist/moment_parse.py b/sandbox/grist/moment_parse.py
index 0a18fcf0..c6a5cdc8 100644
--- a/sandbox/grist/moment_parse.py
+++ b/sandbox/grist/moment_parse.py
@@ -47,6 +47,7 @@ DATE_TOKENS_REGEX = re.compile("("+("|".join(DATE_TOKENS))+")")
 # List of separators to replace and match any standard date/time separators
 SEP = r"[\s/.\-:,]*"
 SEP_REGEX = re.compile(SEP)
+SEP_REPLACEMENT = SEP.replace("\\", "\\\\")
 
 # Maps date parse format to compile regex
 FORMAT_CACHE = {}
@@ -77,7 +78,8 @@ def parse(date_string, parse_format, zonelabel='UTC', override_current_date=None
     # e.g. "MM-YY" -> "(?P<mm>\d{1,2})-(?P<yy>\d{2})"
     # Note that DATE_TOKENS is ordered so that the longer letter chains are recognized first
     tokens = DATE_TOKENS_REGEX.split(parse_format)
-    tokens = [DATE_TOKENS[t] if t in DATE_TOKENS else SEP_REGEX.sub(SEP, t) for t in tokens]
+    tokens = [DATE_TOKENS[t] if t in DATE_TOKENS else SEP_REGEX.sub(SEP_REPLACEMENT, t)
+              for t in tokens]
 
     # Compile new token string ignoring case (for month names)
     parser = re.compile(''.join(tokens), re.I)
diff --git a/sandbox/grist/objtypes.py b/sandbox/grist/objtypes.py
index 11739643..c50771a9 100644
--- a/sandbox/grist/objtypes.py
+++ b/sandbox/grist/objtypes.py
@@ -163,14 +163,16 @@ def encode_object(value):
   Returns ['U', repr(value)] if it fails to encode otherwise.
   """
   try:
-    if isinstance(value, (str, unicode, float, bool)) or value is None:
+    if isinstance(value, (six.text_type, float, bool)) or value is None:
       return value
-    elif isinstance(value, (long, int)):
+    elif isinstance(value, six.binary_type):
+      return value.decode('utf8')
+    elif isinstance(value, six.integer_types):
       if not is_int_short(value):
         raise UnmarshallableError("Integer too large")
       return value
     elif isinstance(value, AltText):
-      return str(value)
+      return six.text_type(value)
     elif isinstance(value, records.Record):
       return ['R', value._table.table_id, value._row_id]
     elif isinstance(value, RecordStub):
@@ -210,13 +212,6 @@ def decode_object(value):
   """
   try:
     if not isinstance(value, (list, tuple)):
-      if isinstance(value, unicode):
-        # TODO For now, the sandbox uses binary strings throughout; see TODO in main.py for more
-        # on this. Strings that come from JS become Python binary strings, and we will not see
-        # unicode here. But we may see it if unmarshalling data that comes from DB, since
-        # DocStorage encodes/decodes values by marshaling JS strings as unicode. For consistency,
-        # convert those unicode strings to binary strings too.
-        return value.encode('utf8')
       return value
     code = value[0]
     args = value[1:]
diff --git a/sandbox/grist/repl.py b/sandbox/grist/repl.py
index 76eb8fb4..b9ece68f 100644
--- a/sandbox/grist/repl.py
+++ b/sandbox/grist/repl.py
@@ -6,9 +6,10 @@ slight changes in order to be convenient for Grist's purposes
 
 import code
 import sys
-from StringIO import StringIO
 from collections import namedtuple
 
+import six
+
 SUCCESS    = 0
 INCOMPLETE = 1
 ERROR      = 2
@@ -38,7 +39,7 @@ class REPLInterpreter(code.InteractiveInterpreter):
     old_stdout = sys.stdout
     old_stderr = sys.stderr
 
-    user_output = StringIO()
+    user_output = six.StringIO()
 
     self.error_text = ""
     try:
@@ -67,7 +68,10 @@ class REPLInterpreter(code.InteractiveInterpreter):
         sys.stderr = old_stderr
 
     program_output = user_output.getvalue()
-    user_output.close()
+    try:
+      user_output.close()
+    except:
+      pass
 
     return EvalTuple(program_output, self.error_text, status)
 
diff --git a/sandbox/grist/test_codebuilder.py b/sandbox/grist/test_codebuilder.py
index 2e19e740..0fa00f95 100644
--- a/sandbox/grist/test_codebuilder.py
+++ b/sandbox/grist/test_codebuilder.py
@@ -92,7 +92,6 @@ class TestCodeBuilder(unittest.TestCase):
 
     # Check for reasonable behaviour with non-empty text and no statements.
     self.assertEqual(make_body('# comment'), '# comment\npass')
-    self.assertEqual(make_body('\\'), '\\\npass')
 
     self.assertEqual(make_body('rec = 1'), "# rec = 1\n" +
                      "raise SyntaxError('Grist disallows assignment " +
diff --git a/sandbox/grist/test_functions.py b/sandbox/grist/test_functions.py
index 42347a40..701f811a 100644
--- a/sandbox/grist/test_functions.py
+++ b/sandbox/grist/test_functions.py
@@ -1,5 +1,9 @@
 import doctest
 import os
+import re
+
+import six
+
 import functions
 import moment
 
@@ -15,6 +19,12 @@ def date_tearDown(doc_test):
   # pylint: disable=unused-argument
   functions.date._get_global_tz = _old_date_get_global_tz
 
+class Py23DocChecker(doctest.OutputChecker):
+  def check_output(self, want, got, optionflags):
+    if six.PY3:
+      want = re.sub(r"^u'(.*?)'$", r"'\1'", want)
+      want = re.sub(r'^u"(.*?)"$', r'"\1"', want)
+    return doctest.OutputChecker.check_output(self, want, got, optionflags)
 
 # This works with the unittest module to turn all the doctests in the functions' doc-comments into
 # unittest test cases.
@@ -26,8 +36,8 @@ def load_tests(loader, tests, ignore):
   tests.addTests(doctest.DocTestSuite(functions.logical))
   tests.addTests(doctest.DocTestSuite(functions.math))
   tests.addTests(doctest.DocTestSuite(functions.stats))
-  tests.addTests(doctest.DocTestSuite(functions.text))
+  tests.addTests(doctest.DocTestSuite(functions.text, checker=Py23DocChecker()))
   tests.addTests(doctest.DocTestSuite(functions.schedule,
                                       setUp = date_setUp, tearDown = date_tearDown))
-  tests.addTests(doctest.DocTestSuite(functions.lookup))
+  tests.addTests(doctest.DocTestSuite(functions.lookup, checker=Py23DocChecker()))
   return tests
diff --git a/sandbox/grist/test_relabeling.py b/sandbox/grist/test_relabeling.py
index 6ca6043f..ef55b992 100644
--- a/sandbox/grist/test_relabeling.py
+++ b/sandbox/grist/test_relabeling.py
@@ -256,7 +256,7 @@ class TestRelabeling(unittest.TestCase):
     self._do_test_renumber_ends([])
 
   def test_renumber_endpoints2(self):
-    self._do_test_renumber_ends(zip("abcd", [40,50,60,70]))
+    self._do_test_renumber_ends(list(zip("abcd", [40,50,60,70])))
 
   def _do_test_renumber_ends(self, initial):
     # Test insertions that happen together on the left and on the right.
diff --git a/sandbox/grist/test_renames.py b/sandbox/grist/test_renames.py
index e4126bf8..a2aca08d 100644
--- a/sandbox/grist/test_renames.py
+++ b/sandbox/grist/test_renames.py
@@ -330,23 +330,23 @@ class TestRenames(test_engine.EngineTestCase):
   def test_renames_with_non_ascii(self):
     # Test that presence of unicode does not interfere with formula adjustments for renaming.
     self.load_sample(self.sample)
-    self.add_column("Address", "CityUpper", formula="'Øî'+$city.upper()+'áü'")
+    self.add_column("Address", "CityUpper", formula=u"'Øî'+$city.upper()+'áü'")
     out_actions = self.apply_user_action(["RenameColumn", "Address", "city", "ciudad"])
     self.assertPartialOutActions(out_actions, { "stored": [
       ["RenameColumn", "Address", "city", "ciudad"],
       ["ModifyColumn", "People", "city", {"formula": "$addr.ciudad"}],
-      ["ModifyColumn", "Address", "CityUpper", {"formula": "'Øî'+$ciudad.upper()+'áü'"}],
+      ["ModifyColumn", "Address", "CityUpper", {"formula": u"'Øî'+$ciudad.upper()+'áü'"}],
       ["BulkUpdateRecord", "_grist_Tables_column", [21, 24, 25], {
         "colId": ["ciudad", "city", "CityUpper"],
-        "formula": ["", "$addr.ciudad", "'Øî'+$ciudad.upper()+'áü'"],
+        "formula": ["", "$addr.ciudad", u"'Øî'+$ciudad.upper()+'áü'"],
       }]
     ]})
     self.assertTableData("Address", cols="all", data=[
       ["id",  "ciudad",     "CityUpper"],
-      [11,    "New York",   "ØîNEW YORKáü"],
-      [12,    "Colombia",   "ØîCOLOMBIAáü"],
-      [13,    "New Haven",  "ØîNEW HAVENáü"],
-      [14,    "West Haven", "ØîWEST HAVENáü"],
+      [11,    "New York",   u"ØîNEW YORKáü"],
+      [12,    "Colombia",   u"ØîCOLOMBIAáü"],
+      [13,    "New Haven",  u"ØîNEW HAVENáü"],
+      [14,    "West Haven", u"ØîWEST HAVENáü"],
     ])
 
   def test_rename_updates_properties(self):
diff --git a/sandbox/grist/test_types.py b/sandbox/grist/test_types.py
index 2199f123..f2d9c4f2 100644
--- a/sandbox/grist/test_types.py
+++ b/sandbox/grist/test_types.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # pylint: disable=line-too-long
+import six
 
 import logger
 import testutil
@@ -25,7 +26,7 @@ class TestTypes(test_engine.EngineTestCase):
       "Types": [
         ["id", "text",     "numeric",  "int",      "bool",     "date"],
         [11,   "New York", "New York", "New York", "New York", "New York"],
-        [12,   "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö"],
+        [12,   u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö"],
         [13,   False,      False,      False,      False,      False],
         [14,   True,       True,       True,       True,       True],
         [15,   1509556595, 1509556595, 1509556595, 1509556595, 1509556595],
@@ -61,20 +62,20 @@ class TestTypes(test_engine.EngineTestCase):
 
     self.assertPartialOutActions(out_actions, {
       "stored": [["BulkUpdateRecord", "Types", self.all_row_ids, {
-        "text":    [None,"","1","0","8.153","1509556595","True","False","Chîcágö","New York"],
-        "numeric": [None, None, 1.0, 0.0, 8.153, 1509556595.0, 1.0, 0.0, "Chîcágö", "New York"],
-        "int":     [None, None, 1, 0, 8, 1509556595, 1, 0, "Chîcágö", "New York"],
-        "bool":    [False, False, True, False, True, True, True, False, "Chîcágö", "New York"],
+        "text":    [None,"","1","0","8.153","1509556595","True","False",u"Chîcágö","New York"],
+        "numeric": [None, None, 1.0, 0.0, 8.153, 1509556595.0, 1.0, 0.0, u"Chîcágö", "New York"],
+        "int":     [None, None, 1, 0, 8, 1509556595, 1, 0, u"Chîcágö", "New York"],
+        "bool":    [False, False, True, False, True, True, True, False, u"Chîcágö", "New York"],
         "date":    [None, None, 1.0, 0.0, 8.153, 1509556595.0, 1.0, 0.0, 1548115200.0, "New York"]
         }],
         ["UpdateRecord", "Formulas", 1, {"division": 0.0}],
       ],
       "undo": [["BulkUpdateRecord", "Types", self.all_row_ids, {
-        "text":    ["New York", "Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None],
-        "numeric": ["New York", "Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None],
-        "int":     ["New York", "Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None],
-        "bool":    ["New York", "Chîcágö", False, True, 1509556595, 8.153, False, True, "", None],
-        "date":    ["New York", "Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None]
+        "text":    ["New York", u"Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None],
+        "numeric": ["New York", u"Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None],
+        "int":     ["New York", u"Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None],
+        "bool":    ["New York", u"Chîcágö", False, True, 1509556595, 8.153, False, True, "", None],
+        "date":    ["New York", u"Chîcágö", False, True, 1509556595, 8.153, 0, 1, "", None]
         }],
         ["UpdateRecord", "Formulas", 1, {"division": 0.5}],
       ]
@@ -90,7 +91,7 @@ class TestTypes(test_engine.EngineTestCase):
       [16,   "1509556595", 1509556595, 1509556595, True,       1509556595.0],
       [17,   "True",       1.0,        1,          True,       1.0],
       [18,   "False",      0.0,        0,          False,      0.0],
-      [19,   "Chîcágö",    "Chîcágö",  "Chîcágö",  "Chîcágö",  1548115200.0],
+      [19,   u"Chîcágö",    u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  1548115200.0],
       [20,   "New York",   "New York", "New York", "New York", "New York"]
     ])
 
@@ -184,7 +185,7 @@ class TestTypes(test_engine.EngineTestCase):
     self.assertTableData("Types", data=[
       ["id", "text",      "numeric",   "int",       "bool",      "date"],
       [11,   "New York",  "New York",  "New York",  "New York",  "New York"],
-      [12,   "Chîcágö",   "Chîcágö",   "Chîcágö",   "Chîcágö",   "Chîcágö"],
+      [12,   u"Chîcágö",   u"Chîcágö",   u"Chîcágö",   u"Chîcágö",   u"Chîcágö"],
       [13,   False,       "False",     "False",     "False",     "False"],
       [14,   True,        "True",      "True",      "True",      "True"],
       [15,   1509556595,  "1509556595.0","1509556595","1509556595","1509556595.0"],
@@ -283,7 +284,7 @@ class TestTypes(test_engine.EngineTestCase):
     self.assertTableData("Types", data=[
       ["id", "text",     "numeric",  "int",      "bool",     "date"],
       [11,   "New York", "New York", "New York", "New York", "New York"],
-      [12,   "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö"],
+      [12,   u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö"],
       [13,   0.0,        False,      0.0,        0.0,        0.0],
       [14,   1.0,        True,       1.0,        1.0,        1.0],
       [15,   1509556595, 1509556595, 1509556595, 1509556595, 1509556595],
@@ -327,15 +328,13 @@ class TestTypes(test_engine.EngineTestCase):
         ["BulkUpdateRecord", "Types", [13, 14, 16, 19],
          {"numeric": [0, 1, 8, None]}],
         ["UpdateRecord", "_grist_Tables_column", 22, {"type": "Int"}],
-        ["UpdateRecord", "Formulas", 1, {"division": 0}],
-      ],
+      ] + six.PY2 * [["UpdateRecord", "Formulas", 1, {"division": 0}]],  # Only in Python 2 due to integer division,
       "undo": [
         ["BulkUpdateRecord", "Types", [13, 14, 16, 19],
           {"numeric": [False, True, 8.153, ""]}],
         ["ModifyColumn", "Types", "numeric", {"type": "Numeric"}],
         ["UpdateRecord", "_grist_Tables_column", 22, {"type": "Numeric"}],
-        ["UpdateRecord", "Formulas", 1, {"division": 0.5}],
-      ]
+      ] + six.PY2 * [["UpdateRecord", "Formulas", 1, {"division": 0.5}]],  # Only in Python 2 due to integer division
     })
 
     # Test Int -> Int conversion
@@ -383,7 +382,7 @@ class TestTypes(test_engine.EngineTestCase):
     self.assertTableData("Types", data=[
       ["id", "text",     "numeric",  "int",      "bool",     "date"],
       [11,   "New York", "New York", "New York", "New York", "New York"],
-      [12,   "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö"],
+      [12,   u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö"],
       [13,   0,          0,          False,      0,          0],
       [14,   1,          1,          True,       1,          1],
       [15,   1509556595, 1509556595, 1509556595, 1509556595, 1509556595],
@@ -428,15 +427,13 @@ class TestTypes(test_engine.EngineTestCase):
         ["BulkUpdateRecord", "Types", [15, 16, 17, 18, 19, 20],
           {"numeric": [True, True, False, True, False, False]}],
         ["UpdateRecord", "_grist_Tables_column", 22, {"type": "Bool"}],
-        ["UpdateRecord", "Formulas", 1, {"division": 0}],
-      ],
+      ] + six.PY2 * [["UpdateRecord", "Formulas", 1, {"division": 0}]],  # Only in Python 2 due to integer division,
       "undo": [
         ["BulkUpdateRecord", "Types", [15, 16, 17, 18, 19, 20],
           {"numeric": [1509556595.0, 8.153, 0.0, 1.0, "", None]}],
         ["ModifyColumn", "Types", "numeric", {"type": "Numeric"}],
         ["UpdateRecord", "_grist_Tables_column", 22, {"type": "Numeric"}],
-        ["UpdateRecord", "Formulas", 1, {"division": 0.5}],
-      ]
+      ] + six.PY2 * [["UpdateRecord", "Formulas", 1, {"division": 0.5}]],  # Only in Python 2 due to integer division
     })
 
     # Test Int -> Bool conversion
@@ -484,7 +481,7 @@ class TestTypes(test_engine.EngineTestCase):
     self.assertTableData("Types", data=[
       ["id", "text",     "numeric",  "int",      "bool",     "date"],
       [11,   "New York", "New York", "New York", "New York", "New York"],
-      [12,   "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö"],
+      [12,   u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö"],
       [13,   False,      False,      False,      False,      False],
       [14,   True,       True,       True,       True,       True],
       [15,   True,       True,       True,       1509556595, True],
@@ -585,7 +582,7 @@ class TestTypes(test_engine.EngineTestCase):
     self.assertTableData("Types", data=[
       ["id", "text",     "numeric",  "int",      "bool",     "date"],
       [11,   "New York", "New York", "New York", "New York", "New York"],
-      [12,   "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö",  "Chîcágö"],
+      [12,   u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö",  u"Chîcágö"],
       [13,   0.0,        0.0,        0.0,        0.0,        False],
       [14,   1.0,        1.0,        1.0,        1.0,        True],
       [15,   1509556595, 1509556595, 1509556595, 1509556595, 1509556595],
diff --git a/sandbox/grist/test_urllib_patch.py b/sandbox/grist/test_urllib_patch.py
new file mode 100644
index 00000000..ed4c1452
--- /dev/null
+++ b/sandbox/grist/test_urllib_patch.py
@@ -0,0 +1,19 @@
+# coding=utf-8
+import unittest
+import urllib
+
+import six
+
+from urllib_patch import original_quote
+
+
+class TestUrllibPatch(unittest.TestCase):
+  def test_patched_quote(self):
+    self.assertEqual(urllib.quote( "a b"), u"a%20b")
+    self.assertEqual(urllib.quote(u"a b"), u"a%20b")
+    self.assertEqual(urllib.quote(u"a é"), u"a%20%C3%A9")
+
+    self.assertEqual(original_quote( "a b"), u"a%20b")
+    self.assertEqual(original_quote(u"a b"), u"a%20b")
+    if six.PY3:  # python 2 original quote can't handle non-ascii
+      self.assertEqual(original_quote(u"a é"), u"a%20%C3%A9")
diff --git a/sandbox/grist/testscript.json b/sandbox/grist/testscript.json
index 66c3d4ac..df932d1b 100644
--- a/sandbox/grist/testscript.json
+++ b/sandbox/grist/testscript.json
@@ -2768,7 +2768,7 @@
     ["APPLY", {
       "USER_ACTIONS": [
         // Access to usercode before and after re-generation
-        ["EvalCode", "list(Students.all.firstName)", null],
+        ["EvalCode", "list(map(str, Students.all.firstName))", null],
         ["UpdateRecord", "Students", 1, {"firstName": "2e6"}],
         ["ModifyColumn", "Students", "firstName", { "type" : "Numeric" }],
         ["EvalCode", "list(Students.all.firstName)", 6],
@@ -2778,7 +2778,7 @@
       "ACTIONS": {
         "stored": [
           ["AddRecord", "_grist_REPL_Hist", 6,
-            {"code": "list(Students.all.firstName)", "errorText": "", "outputText": "['Barack', 'George W', 'Bill', 'George H', 'Ronald', 'Jimmy', 'Gerald']\n"}],
+            {"code": "list(map(str, Students.all.firstName))", "errorText": "", "outputText": "['Barack', 'George W', 'Bill', 'George H', 'Ronald', 'Jimmy', 'Gerald']\n"}],
 
           ["UpdateRecord", "Students", 1, {"firstName": "2e6"}],
           ["ModifyColumn", "Students", "firstName", {"type": "Numeric"}],
@@ -2808,7 +2808,7 @@
           ["ModifyColumn", "Students", "firstName", {"type": "Text"}],
           ["UpdateRecord", "_grist_Tables_column", 1, {"type": "Text"}],
 
-          ["UpdateRecord", "_grist_REPL_Hist", 6, {"code": "list(Students.all.firstName)",
+          ["UpdateRecord", "_grist_REPL_Hist", 6, {"code": "list(map(str, Students.all.firstName))",
            "errorText": "", "outputText": "['Barack', 'George W', 'Bill', 'George H', 'Ronald', 'Jimmy', 'Gerald']\n"}],
           ["UpdateRecord", "_grist_REPL_Hist", 6, {"code": "list(Students.all.firstName)",
             "errorText": "",
@@ -2825,7 +2825,7 @@
     ["APPLY", {
       "USER_ACTIONS": [
         // Syntax Error
-        ["EvalCode", "*!@&$fjjj112#(8!", null],
+        ["EvalCode", "not correct c", null],
         // Other continuations
         ["EvalCode", "map(filter, ", null],
         ["EvalCode", "[1,2,3,", null],
@@ -2834,15 +2834,14 @@
         ["EvalCode", "sys.exit(0)", null],
         // User reassignment of sys.stdout/sys.stderr
         ["EvalCode", "sys.stdout = None", null],
-        ["EvalCode", "delattr(sys.stderr, 'close')", null],
         ["EvalCode", "setattr(sys.stdout, 'getvalue', lambda : 2)", null],
-        ["EvalCode", "def foo():\n global stdout\n exec 'stdout = 2'\n", null],
+        ["EvalCode", "def foo():\n global stdout\n exec('stdout = 2')\n", null],
         ["EvalCode", "setattr(sys.stderr, 'close', foo)", null]
       ],
       "ACTIONS": {
         "stored": [
           ["AddRecord", "_grist_REPL_Hist", 7,
-            {"code": "*!@&$fjjj112#(8!", "errorText": "  File \"<input>\", line 1\n    *!@&$fjjj112#(8!\n    ^\nSyntaxError: invalid syntax\n", "outputText": ""}],
+            {"code": "not correct c", "errorText": "  File \"<input>\", line 1\n    not correct c\n                ^\nSyntaxError: invalid syntax\n", "outputText": ""}],
           ["AddRecord", "_grist_REPL_Hist", 8,
             {"code": "import sys", "errorText": "", "outputText": ""}],
           ["AddRecord", "_grist_REPL_Hist", 9,
@@ -2850,15 +2849,13 @@
           ["AddRecord", "_grist_REPL_Hist", 10,
             {"code": "sys.stdout = None", "errorText": "", "outputText": ""}],
           ["AddRecord", "_grist_REPL_Hist", 11,
-            {"code": "delattr(sys.stderr, 'close')", "errorText": "Traceback (most recent call last):\n  File \"<input>\", line 1, in <module>\nAttributeError: StringIO instance has no attribute 'close'\n", "outputText": ""}],
-          ["AddRecord", "_grist_REPL_Hist", 12,
             {"code": "setattr(sys.stdout, 'getvalue', lambda : 2)", "errorText": "", "outputText": 2}],
+          ["AddRecord", "_grist_REPL_Hist", 12,
+            {"code": "def foo():\n global stdout\n exec('stdout = 2')\n", "errorText": "", "outputText": ""}],
           ["AddRecord", "_grist_REPL_Hist", 13,
-            {"code": "def foo():\n global stdout\n exec 'stdout = 2'\n", "errorText": "", "outputText": ""}],
-          ["AddRecord", "_grist_REPL_Hist", 14,
             {"code": "setattr(sys.stderr, 'close', foo)", "errorText": "", "outputText": ""}]
         ],
-        "direct": [true, true, true, true, true, true, true, true],
+        "direct": [true, true, true, true, true, true, true],
         "undo": [
           ["RemoveRecord", "_grist_REPL_Hist", 7],
           ["RemoveRecord", "_grist_REPL_Hist", 8],
@@ -2866,10 +2863,9 @@
           ["RemoveRecord", "_grist_REPL_Hist", 10],
           ["RemoveRecord", "_grist_REPL_Hist", 11],
           ["RemoveRecord", "_grist_REPL_Hist", 12],
-          ["RemoveRecord", "_grist_REPL_Hist", 13],
-          ["RemoveRecord", "_grist_REPL_Hist", 14]
+          ["RemoveRecord", "_grist_REPL_Hist", 13]
         ],
-        "retValue" : [true,false,false,true,true,true,true,true,true,true ]
+        "retValue" : [true,false,false,true,true,true,true,true,true ]
       }
     }]
   ]
diff --git a/sandbox/grist/testutil.py b/sandbox/grist/testutil.py
index 9a784755..5eaece7e 100644
--- a/sandbox/grist/testutil.py
+++ b/sandbox/grist/testutil.py
@@ -59,7 +59,7 @@ def parse_testscript(script_path=None):
         all_lines.append(line)
   full_text = "".join(all_lines)
 
-  script = byteify(json.loads(full_text))
+  script = json.loads(full_text)
 
   samples = {}
   test_cases = []
@@ -109,16 +109,6 @@ def parse_test_sample(obj, samples={}):
   return {"SCHEMA": schema, "DATA": data}
 
 
-def byteify(data):
-  """
-  Convert all unicode strings in a parsed JSON object into utf8-encoded strings. We deal with
-  utf8-encoded strings throughout the test.
-  """
-  if isinstance(data, unicode):
-    return data.encode('utf-8')
-  return actions.convert_recursive_helper(byteify, data)
-
-
 def replace_nans(data):
   """
   Convert all NaNs and Infinities in the data to descriptive strings, since they cannot be
diff --git a/sandbox/grist/textbuilder.py b/sandbox/grist/textbuilder.py
index 0fe99c0e..44423864 100644
--- a/sandbox/grist/textbuilder.py
+++ b/sandbox/grist/textbuilder.py
@@ -157,7 +157,11 @@ class Combiner(Builder):
   def __init__(self, parts):
     self._parts = parts
     self._offsets = []
-    text_parts = [(p if isinstance(p, basestring) else p.get_text()) for p in self._parts]
+    text_parts = [
+      (p if isinstance(p, six.text_type) else
+       p.decode('utf8') if isinstance(p, six.binary_type) else
+       p.get_text())
+      for p in self._parts]
     self._text = ''.join(text_parts)
 
     offset = 0
diff --git a/sandbox/grist/urllib_patch.py b/sandbox/grist/urllib_patch.py
new file mode 100644
index 00000000..9bad03f0
--- /dev/null
+++ b/sandbox/grist/urllib_patch.py
@@ -0,0 +1,16 @@
+import urllib
+
+import six
+from six.moves import urllib_parse
+
+original_quote = urllib_parse.quote
+
+def patched_quote(s, safe='/'):
+  if isinstance(s, six.text_type):
+    s = s.encode('utf8')
+  result = original_quote(s, safe=safe)
+  if isinstance(result, six.binary_type):
+    result = result.decode('utf8')
+  return result
+
+urllib.quote = patched_quote
diff --git a/sandbox/grist/useractions.py b/sandbox/grist/useractions.py
index 79f0de2a..f870130b 100644
--- a/sandbox/grist/useractions.py
+++ b/sandbox/grist/useractions.py
@@ -5,6 +5,7 @@ import json
 import sys
 
 import six
+from six.moves import xrange
 
 import acl
 from acl_formula import parse_acl_formula_json
@@ -109,7 +110,7 @@ def from_repr(user_action):
   try:
     return action_type(*user_action[1:])
   except TypeError as e:
-    raise TypeError("%s: %s" % (user_action[0], e.message))
+    raise TypeError("%s: %s" % (user_action[0], str(e)))
 
 def _make_clean_col_info(col_info, col_id=None):
   """
@@ -332,7 +333,7 @@ class UserActions(object):
 
     # Invalidate new records, including the omitted columns that may have default formulas,
     # in order to get dynamically-computed default values.
-    omitted_cols = table.all_columns.viewkeys() - column_values.viewkeys()
+    omitted_cols = six.viewkeys(table.all_columns) - six.viewkeys(column_values)
     self._engine.invalidate_records(table_id, filled_row_ids, data_cols_to_recompute=omitted_cols)
 
     return filled_row_ids
@@ -599,18 +600,16 @@ class UserActions(object):
         col_rec = self._docmodel.get_column_rec(formula_table, formula_col)
         # Create a patch and append to the list for this col_rec.
         name = col_id or table_id
-        # Positions are obtained from unicode version of formulas, so that's what we must patch
-        formula = col_rec.formula.decode('utf8')
+        formula = col_rec.formula
         patch = textbuilder.make_patch(formula, pos, pos + len(name), new_name)
         patches_map.setdefault(col_rec, []).append(patch)
 
-    # Apply the collected patches to each affected formula, converting to unicode to apply the
-    # patches and back to byte string for how we maintain string values.
+    # Apply the collected patches to each affected formula
     result = {}
-    for col_rec, patches in six.iteritems(patches_map):
-      formula = col_rec.formula.decode('utf8')
+    for col_rec, patches in patches_map.items():
+      formula = col_rec.formula
       replacer = textbuilder.Replacer(textbuilder.Text(formula), patches)
-      result[col_rec] = replacer.get_text().encode('utf8')
+      result[col_rec] = replacer.get_text()
     return result
 
 
diff --git a/sandbox/grist/usertypes.py b/sandbox/grist/usertypes.py
index d02596a0..5e4400b9 100644
--- a/sandbox/grist/usertypes.py
+++ b/sandbox/grist/usertypes.py
@@ -12,7 +12,6 @@ data structure for values of the wrong type, and the memory savings aren't that
 the extra complexity.
 """
 import csv
-import cStringIO
 import datetime
 import json
 import six
@@ -31,7 +30,7 @@ _type_defaults = {
   'Attachments':  None,
   'Blob':         None,
   'Bool':         False,
-  'Choice':       '',
+  'Choice':       u'',
   'ChoiceList':   None,
   'Date':         None,
   'DateTime':     None,
@@ -42,7 +41,7 @@ _type_defaults = {
   'PositionNumber': float('inf'),
   'Ref':          0,
   'RefList':      None,
-  'Text':         '',
+  'Text':         u'',
 }
 
 def get_type_default(col_type):
@@ -131,10 +130,7 @@ class BaseColumnType(object):
     except Exception as e:
       # If conversion failed, return a string to serve as alttext.
       try:
-        if isinstance(value_to_convert, six.text_type):
-          # str() will fail for a non-ascii unicode object, which needs an explicit encoding.
-          return value_to_convert.encode('utf8')
-        return str(value_to_convert)
+        return six.text_type(value_to_convert)
       except Exception:
         # If converting to string failed, we should still produce something.
         return objtypes.safe_repr(value_to_convert)
@@ -157,7 +153,12 @@ class Text(BaseColumnType):
   """
   @classmethod
   def do_convert(cls, value):
-    return str(value) if value is not None else None
+    if isinstance(value, six.binary_type):
+      return value.decode('utf8')
+    elif value is None:
+      return None
+    else:
+      return six.text_type(value)
 
   @classmethod
   def is_right_type(cls, value):
@@ -176,11 +177,11 @@ class Blob(BaseColumnType):
   """
   @classmethod
   def do_convert(cls, value):
-    return str(value) if value is not None else None
+    return value
 
   @classmethod
   def is_right_type(cls, value):
-    return isinstance(value, (basestring, NoneType))
+    return isinstance(value, (six.binary_type, NoneType))
 
 
 class Any(BaseColumnType):
@@ -190,7 +191,7 @@ class Any(BaseColumnType):
   @classmethod
   def do_convert(cls, value):
     # Convert AltText values to plain text when assigning to type Any.
-    return str(value) if isinstance(value, AltText) else value
+    return six.text_type(value) if isinstance(value, AltText) else value
 
 
 class Bool(BaseColumnType):
@@ -206,7 +207,7 @@ class Bool(BaseColumnType):
     if isinstance(value, (float, six.integer_types)):
       return True
     if isinstance(value, AltText):
-      value = str(value)
+      value = six.text_type(value)
     if isinstance(value, six.string_types):
       if value.lower() in ("false", "no", "0"):
         return False
@@ -334,13 +335,13 @@ class ChoiceList(BaseColumnType):
       # If it's a string that looks like JSON, try to parse it as such.
       if value.startswith('['):
         try:
-          return tuple(str(item) for item in json.loads(value))
+          return tuple(six.text_type(item) for item in json.loads(value))
         except Exception:
           pass
       return value
     else:
       # Accepts other kinds of iterables; if that doesn't work, fail the conversion too.
-      return tuple(str(item) for item in value)
+      return tuple(six.text_type(item) for item in value)
 
   @classmethod
   def is_right_type(cls, value):
@@ -362,7 +363,7 @@ class ChoiceList(BaseColumnType):
   def toString(cls, value):
     if isinstance(value, (tuple, list)):
       try:
-        buf = cStringIO.StringIO()
+        buf = six.StringIO()
         csv.writer(buf).writerow(value)
         return buf.getvalue().strip()
       except Exception:
@@ -434,7 +435,7 @@ class Reference(Id):
   @classmethod
   def typeConvert(cls, value, ref_table, visible_col=None):  # pylint: disable=arguments-differ
     if ref_table and visible_col:
-      return ref_table.lookupOne(**{visible_col: value}) or str(value)
+      return ref_table.lookupOne(**{visible_col: value}) or six.text_type(value)
     else:
       return value