diff --git a/400_xowa/src/gplx/xowa/mediawiki/XophpArray.java b/400_xowa/src/gplx/xowa/mediawiki/XophpArray.java
index a42a664a4..ae35a1682 100644
--- a/400_xowa/src/gplx/xowa/mediawiki/XophpArray.java
+++ b/400_xowa/src/gplx/xowa/mediawiki/XophpArray.java
@@ -30,10 +30,14 @@ import gplx.core.brys.Bry_bfr_able;
 import gplx.core.strings.String_bldr;
 import gplx.core.strings.String_bldr_;
 
+import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
 
-// REF.PHP: https://www.php.net/manual/en/language.types.array.php
-// also has static functions; REF.PHP: https://www.php.net/manual/en/ref.array.php
+// REF.PHP:https://www.php.net/manual/en/language.types.array.php
+// also has static functions; REF.PHP:https://www.php.net/manual/en/ref.array.php
 public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 	private final Ordered_hash hash = Ordered_hash_.New();
 	private int newMemberIdx;
@@ -138,6 +142,9 @@ public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 		XophpArrayItm itm = (XophpArrayItm)hash.Get_by(key);
 		return itm == null ? null : (T)itm.Val();
 	}
+	public XophpArrayItm Get_by_itm(String key) {
+		return (XophpArrayItm)hash.Get_by(key);
+	}
 	public void Set(int key, Object val) {
 		this.Set(XophpArrayItm.NewInt(key, val));
 	}
@@ -160,6 +167,9 @@ public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 			hash.Del(itm.Key());
 		}
 	}
+	public void Del_by(String key) {
+		hash.Del(key);
+	}
 	public XophpArrayItm[] To_ary() {
 		return (XophpArrayItm[])hash.To_ary(XophpArrayItm.class);
 	}
@@ -309,7 +319,7 @@ public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 		return len == 0 ? null : ((XophpArrayItm)array.hash.Get_at(len - 1)).Val();
 	}
 
-	// REF.PHP: https://www.php.net/manual/en/function.array-values.php
+	// REF.PHP:https://www.php.net/manual/en/function.array-values.php
 	public static XophpArray array_values(XophpArray array) {
 		XophpArray rv = new XophpArray();
 		int len = array.Len();
@@ -482,7 +492,7 @@ public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 		return sb.To_str_and_clear();
 	}
 
-	// REF.PHP: https://www.php.net/manual/en/function.in-array.php
+	// REF.PHP:https://www.php.net/manual/en/function.in-array.php
 	public static boolean in_array(Object needle, XophpArray haystack) {return in_array(needle, haystack, false);}
 	public static boolean in_array(Object needle, XophpArray haystack, boolean strict) {
 		// if strict, cache needleType
@@ -519,7 +529,7 @@ public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 		return false;
 	}
 
-	// REF.PHP: https://www.php.net/manual/en/function.array-shift.php
+	// REF.PHP:https://www.php.net/manual/en/function.array-shift.php
 	// Returns the shifted value, or NULL if array is empty or is not an array.
 	public static Object array_shift(XophpArray array) {
 		if (array == null) {
@@ -544,7 +554,7 @@ public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 		return itms[0].Val();
 	}
 
-	// REF.PHP: https://www.php.net/manual/en/function.array-filter.php
+	// REF.PHP:https://www.php.net/manual/en/function.array-filter.php
 	public static final int ARRAY_FILTER_USE_BOTH = 1, ARRAY_FILTER_USE_KEY = 2, ARRAY_FILTER_USE_VAL = 0; // XO:USE_VAL is not PHP
 	public static XophpArray array_filter(XophpArray array) {return array_filter(array, NULL_CALLBACK, 0);}
 	public static XophpArray array_filter(XophpArray array, XophpCallback callback) {return array_filter(array, callback, 0);}
@@ -578,4 +588,70 @@ public class XophpArray<T> implements Bry_bfr_able, Iterable<T> {
 			return !XophpObject_.empty_obj(arg);
 		}
 	}
+	// REF.PHP:https://www.php.net/manual/en/function.array-diff.php
+	public static XophpArray array_diff(XophpArray array1, XophpArray array2, XophpArray... arrays) {
+		// remove elements
+		Map<String, List<String>> valMap = array_diff__build_val_map(array1);
+		int array1_len = array1.Len();
+		array_diff__remove_common_vals(valMap, array1, array2);
+		for (XophpArray array : arrays) {
+			// update map, if array contents changed
+			if (array1_len != array1.Len()) {
+				valMap = array_diff__build_val_map(array1);
+				array1_len = array1.Len();
+			}
+			array_diff__remove_common_vals(valMap, array1, array);
+		}
+		return array1;
+	}
+	private static Map<String, List<String>> array_diff__build_val_map(XophpArray array) {
+		Map<String, List<String>> map = new HashMap<>();
+		int len = array.Len();
+		for (int i = 0; i < len; i++) {
+			XophpArrayItm itm = array.Get_at_itm(i);
+
+			// get val as String
+			String valStr = XophpObject_.ToStr(itm.Val());
+			List<String> keyList = map.get(valStr);
+			if (keyList == null) {
+				keyList = new ArrayList<>();
+				map.put(valStr, keyList);
+			}
+			keyList.add(itm.Key());
+		}
+		return map;
+	}
+	private static void array_diff__remove_common_vals(Map<String, List<String>> lhsValMap, XophpArray lhs, XophpArray rhs) {
+		int rhsLen = rhs.Len();
+		for (int i = 0; i < rhsLen; i++) {
+			XophpArrayItm rhsItm = rhs.Get_at_itm(i);
+			String rhsVal = XophpObject_.ToStr(rhsItm.Val());
+			List<String> lhsKeyList = lhsValMap.get(rhsVal);
+			if (lhsKeyList != null) {
+				for (String lhsKey : lhsKeyList) {
+					lhs.Del_by(lhsKey);
+				}
+			}
+		}
+	}
+	
+	// REF.PHP:https://www.php.net/manual/en/function.array-diff-key
+	public static XophpArray array_diff_key(XophpArray array1, XophpArray array2, XophpArray... arrays) {
+		// remove elements
+		array_diff_key__remove_common_key(array1, array2);
+		for (XophpArray array : arrays) {
+			array_diff_key__remove_common_key(array1, array);
+		}
+		return array1;
+	}
+	private static void array_diff_key__remove_common_key(XophpArray lhs, XophpArray rhs) {
+		int rhsLen = rhs.Len();
+		for (int i = 0; i < rhsLen; i++) {
+			XophpArrayItm rhsItm = rhs.Get_at_itm(i);
+			String rhsKey = rhsItm.Key();
+			if (lhs.Has(rhsKey)) {
+				lhs.Del_by(rhsKey);
+			}
+		}
+	}
 }
diff --git a/400_xowa/src/gplx/xowa/mediawiki/XophpArrayItm.java b/400_xowa/src/gplx/xowa/mediawiki/XophpArrayItm.java
index e92310ccb..47f30e834 100644
--- a/400_xowa/src/gplx/xowa/mediawiki/XophpArrayItm.java
+++ b/400_xowa/src/gplx/xowa/mediawiki/XophpArrayItm.java
@@ -23,8 +23,8 @@ import gplx.String_;
 import gplx.Type_;
 import gplx.core.brys.Bry_bfr_able;
 
-public class XophpArrayItm implements Bry_bfr_able {
-	XophpArrayItm(boolean keyIsInt, int keyAsInt, String key, Object val) {
+public class XophpArrayItm<T> implements Bry_bfr_able {
+	XophpArrayItm(boolean keyIsInt, int keyAsInt, String key, T val) {
 		this.keyIsInt = keyIsInt;
 		this.keyAsInt = keyAsInt;
 		this.key = key;
@@ -33,7 +33,7 @@ public class XophpArrayItm implements Bry_bfr_able {
 	public boolean KeyIsInt() {return keyIsInt;} private final boolean keyIsInt;
 	public int KeyAsInt() {return keyAsInt;} private final int keyAsInt;
 	public String Key() {return key;} private final String key;
-	public Object Val() {return val;} public void Val_(Object v) {this.val = v;} private Object val;
+	public T Val() {return val;} public void Val_(T v) {this.val = v;} private T val;
 
 	public void To_bfr(Bry_bfr bfr) {
 		bfr.Add_str_u8(key).Add_byte_eq();
diff --git a/400_xowa/src/gplx/xowa/mediawiki/XophpObject_.java b/400_xowa/src/gplx/xowa/mediawiki/XophpObject_.java
index 74cbea012..bfc6f2ad7 100644
--- a/400_xowa/src/gplx/xowa/mediawiki/XophpObject_.java
+++ b/400_xowa/src/gplx/xowa/mediawiki/XophpObject_.java
@@ -96,4 +96,9 @@ public class XophpObject_ {
 
     // equivalent to ??
 	public static Object Coalesce(Object o, Object or) {return isset_obj(o) ? o : or;}
+
+	// equivalent to (string)o; see https://www.php.net/manual/en/function.array-diff.php
+	public static String ToStr(Object o) {
+		return o.toString();
+	}
 }
diff --git a/400_xowa/src/gplx/xowa/mediawiki/includes/libs/services/XomwServiceContainer.java b/400_xowa/src/gplx/xowa/mediawiki/includes/libs/services/XomwServiceContainer.java
index 34648e4bd..8e47e4a47 100644
--- a/400_xowa/src/gplx/xowa/mediawiki/includes/libs/services/XomwServiceContainer.java
+++ b/400_xowa/src/gplx/xowa/mediawiki/includes/libs/services/XomwServiceContainer.java
@@ -15,15 +15,12 @@ Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
 package gplx.xowa.mediawiki.includes.libs.services;
 
-import gplx.xowa.mediawiki.XophpArray;
 import gplx.xowa.mediawiki.XophpArray;
 import gplx.xowa.mediawiki.XophpCallback;
 import gplx.xowa.mediawiki.XophpObject_;
 import gplx.xowa.mediawiki.XophpType_;
 /*
 XOTODO:
-* array_diff: https://www.php.net/manual/en/function.array-diff.php
-* array_diff_key: https://www.php.net/manual/en/function.array-diff-key
 * XomwAssert: /vendor/wikimedia/Assert/src
 */
 // MW.SRC:1.33.1
diff --git a/400_xowa/tst/gplx/xowa/mediawiki/XophpArrayStaticTest.java b/400_xowa/tst/gplx/xowa/mediawiki/XophpArrayStaticTest.java
index 9aefd5195..b1c10317e 100644
--- a/400_xowa/tst/gplx/xowa/mediawiki/XophpArrayStaticTest.java
+++ b/400_xowa/tst/gplx/xowa/mediawiki/XophpArrayStaticTest.java
@@ -389,6 +389,60 @@ public class XophpArrayStaticTest {
 		XophpArray.reset(array);
 		Gftest.Eq__str("step one", (String)XophpArray.current(array));
 	}
+	@Test public void array_diff() {
+		// test To_str
+		XophpArray<String> array1 = new XophpArray().Add("a", "0");
+		XophpArray<Integer> arrayInt = new XophpArray().Add("a", 0);
+
+		fxt.Test__eq
+		( new XophpArray<String>()
+		, XophpArray.array_diff(array1, arrayInt)
+		);
+
+		// test many
+		XophpArray<String> array2, array3, array4;
+		array1 = new XophpArray().Add_many("a", "b", "c", "d");
+		array2 = new XophpArray().Add_many("a");
+		array3 = new XophpArray().Add_many("c");
+		array4 = new XophpArray().Add_many("d");
+
+		fxt.Test__eq
+		( new XophpArray<String>().Add(1, "b")
+		, XophpArray.array_diff(array1, array2, array3, array4)
+		);
+
+		// PHP examples
+		// Example #1 array_diff() example
+		array1 = new XophpArray().Add("a", "green").Add_many("red", "blue", "red");
+		array2 = new XophpArray().Add("b", "green").Add_many("yellow", "red");
+
+		fxt.Test__eq
+		( new XophpArray<String>().Add(1, "blue")
+		, XophpArray.array_diff(array1, array2)
+		);
+	}
+	@Test public void array_diff_key() {
+		// PHP examples
+		// Example #1 array_diff_key() example
+		XophpArray<Integer> array1, array2;
+		array1 = new XophpArray<>().Add("blue", 1).Add("red", 2).Add("green", 3).Add("purple", 4);
+		array2 = new XophpArray<>().Add("green", 5).Add("yellow", 7).Add("cyan", 8);
+
+		fxt.Test__eq
+		( new XophpArray<String>().Add("blue", 1).Add("red", 2).Add("purple", 4)
+		, XophpArray.array_diff_key(array1, array2)
+		);
+
+		XophpArray<Integer> array3;
+		array1 = new XophpArray<>().Add("blue", 1).Add("red", 2).Add("green", 3).Add("purple", 4);
+		array2 = new XophpArray<>().Add("green", 5).Add("yellow", 7).Add("cyan", 8);
+		array3 = new XophpArray<>().Add("blue", 6).Add("yellow", 7).Add("mauve", 8);
+
+		fxt.Test__eq
+		( new XophpArray<String>().Add("red", 2).Add("purple", 4)
+		, XophpArray.array_diff_key(array1, array2, array3)
+		);
+	}
 }
 class XophpArray_fxt {
 	public XophpArray Make() {return new XophpArray();}