diff --git a/src/dom/dom.zig b/src/dom/dom.zig
index 9fb3ad79..6a29a937 100644
--- a/src/dom/dom.zig
+++ b/src/dom/dom.zig
@@ -2,11 +2,13 @@ const generate = @import("../generate.zig");
 
 const DOMException = @import("exceptions.zig").DOMException;
 const EventTarget = @import("event_target.zig").EventTarget;
+const DOMImplementation = @import("implementation.zig").DOMImplementation;
 const Nod = @import("node.zig");
 
 pub const Interfaces = generate.Tuple(.{
     DOMException,
     EventTarget,
+    DOMImplementation,
     Nod.Node,
     Nod.Interfaces,
 });
diff --git a/src/dom/implementation.zig b/src/dom/implementation.zig
new file mode 100644
index 00000000..c81aabce
--- /dev/null
+++ b/src/dom/implementation.zig
@@ -0,0 +1,82 @@
+const std = @import("std");
+
+const parser = @import("../netsurf.zig");
+
+const jsruntime = @import("jsruntime");
+const Case = jsruntime.test_utils.Case;
+const checkCases = jsruntime.test_utils.checkCases;
+
+const Document = @import("document.zig").Document;
+const DocumentType = @import("document_type.zig").DocumentType;
+
+// WEB IDL https://dom.spec.whatwg.org/#domimplementation
+pub const DOMImplementation = struct {
+    pub const mem_guarantied = true;
+
+    pub fn _createDocumentType(
+        self: *DOMImplementation,
+        allocator: std.mem.Allocator,
+        qname: []const u8,
+        publicId: []const u8,
+        systemId: []const u8,
+    ) !*parser.DocumentType {
+        _ = self;
+        const cqname = try allocator.dupeZ(u8, qname);
+        defer allocator.free(cqname);
+
+        const cpublicId = try allocator.dupeZ(u8, publicId);
+        defer allocator.free(cpublicId);
+
+        const csystemId = try allocator.dupeZ(u8, systemId);
+        defer allocator.free(csystemId);
+
+        const dt = parser.domImplementationCreateDocumentType(cqname, cpublicId, csystemId);
+        return dt;
+    }
+
+    pub fn _createDocument(
+        self: *DOMImplementation,
+        allocator: std.mem.Allocator,
+        namespace: ?[]const u8,
+        qname: ?[]const u8,
+        doctype: ?*parser.DocumentType,
+    ) !*parser.Document {
+        _ = self;
+        var cnamespace: ?[:0]const u8 = null;
+        if (namespace != null) {
+            cnamespace = try allocator.dupeZ(u8, namespace.?);
+            defer allocator.free(cnamespace.?);
+        }
+
+        var cqname: ?[:0]const u8 = null;
+        if (qname != null) {
+            cqname = try allocator.dupeZ(u8, qname.?);
+            defer allocator.free(cqname.?);
+        }
+
+        const doc = parser.domImplementationCreateDocument(cnamespace, cqname, doctype);
+        return doc;
+    }
+
+    pub fn _createHTMLDocument(_: *DOMImplementation, title: ?[]const u8) *parser.Document {
+        const doc = parser.domImplementationCreateHTMLDocument(title);
+        return doc;
+    }
+};
+
+// Tests
+// -----
+
+pub fn testExecFn(
+    _: std.mem.Allocator,
+    js_env: *jsruntime.Env,
+    comptime _: []jsruntime.API,
+) !void {
+    var getImplementation = [_]Case{
+        .{ .src = "let impl = document.implementation", .ex = "undefined" },
+        .{ .src = "impl.createHTMLDocument();", .ex = "[object Document]" },
+        .{ .src = "impl.createDocument(null, 'foo');", .ex = "[object Document]" },
+        .{ .src = "impl.createDocumentType('foo', 'bar', 'baz');", .ex = "[object DocumentType]" },
+    };
+    try checkCases(js_env, &getImplementation);
+}
diff --git a/src/netsurf.zig b/src/netsurf.zig
index dbb3e61e..0605f005 100644
--- a/src/netsurf.zig
+++ b/src/netsurf.zig
@@ -826,6 +826,54 @@ pub inline fn documentTypeGetSystemId(dt: *DocumentType) []const u8 {
     return stringToData(s.?);
 }
 
+// DOMImplementation
+pub inline fn domImplementationCreateDocument(namespace: ?[:0]const u8, qname: ?[:0]const u8, doctype: ?*DocumentType) *Document {
+    var doc: ?*Document = undefined;
+
+    var ptrnamespace: [*c]const u8 = null;
+    if (namespace != null) {
+        ptrnamespace = namespace.?.ptr;
+    }
+
+    var ptrqname: [*c]const u8 = null;
+    if (qname != null) {
+        ptrqname = qname.?.ptr;
+    }
+
+    _ = c.dom_implementation_create_document(
+        c.DOM_IMPLEMENTATION_XML,
+        ptrnamespace,
+        ptrqname,
+        doctype,
+        null,
+        null,
+        &doc,
+    );
+    return doc.?;
+}
+
+pub inline fn domImplementationCreateDocumentType(qname: [:0]const u8, publicId: [:0]const u8, systemId: [:0]const u8) *DocumentType {
+    var dt: ?*DocumentType = undefined;
+    _ = c.dom_implementation_create_document_type(qname.ptr, publicId.ptr, systemId.ptr, &dt);
+    return dt.?;
+}
+
+pub inline fn domImplementationCreateHTMLDocument(title: ?[]const u8) *Document {
+    _ = title;
+    var doc: ?*Document = undefined;
+    _ = c.dom_implementation_create_document(
+        c.DOM_IMPLEMENTATION_HTML,
+        null,
+        null,
+        null,
+        null,
+        null,
+        &doc,
+    );
+    // TODO set title
+    return doc.?;
+}
+
 // Document
 pub const Document = c.dom_document;
 
@@ -915,7 +963,7 @@ pub fn documentHTMLParseFromFile(filename: [:0]const u8) !*DocumentHTML {
 // The allocator is required to create a null terminated string.
 // The c string allocated is freed by the function.
 // The caller is responsible for closing the document.
-pub fn documentHTMLParseFromStrAlloc(allocator: std.mem.Allocator, str: [:0]const u8) !*DocumentHTML {
+pub fn documentHTMLParseFromStrAlloc(allocator: std.mem.Allocator, str: []const u8) !*DocumentHTML {
     // create a null terminated c string.
     const cstr = try allocator.dupeZ(u8, str);
     defer allocator.free(cstr);
diff --git a/src/run_tests.zig b/src/run_tests.zig
index 8acad71c..3a7dec64 100644
--- a/src/run_tests.zig
+++ b/src/run_tests.zig
@@ -13,6 +13,7 @@ const characterDataTestExecFn = @import("dom/character_data.zig").testExecFn;
 const textTestExecFn = @import("dom/text.zig").testExecFn;
 const HTMLCollectionTestExecFn = @import("dom/html_collection.zig").testExecFn;
 const DOMExceptionTestExecFn = @import("dom/exceptions.zig").testExecFn;
+const DOMImplementationExecFn = @import("dom/implementation.zig").testExecFn;
 
 var doc: *parser.DocumentHTML = undefined;
 
@@ -55,6 +56,7 @@ fn testsAllExecFn(
         textTestExecFn,
         HTMLCollectionTestExecFn,
         DOMExceptionTestExecFn,
+        DOMImplementationExecFn,
     };
 
     inline for (testFns) |testFn| {