diff --git a/src/browser/tests/performance.html b/src/browser/tests/performance.html
index 5aed2cc1..a2647792 100644
--- a/src/browser/tests/performance.html
+++ b/src/browser/tests/performance.html
@@ -43,3 +43,91 @@
     }
   }
 </script>
+
+<script id=mark>
+  {
+    let mark1 = performance.mark("start");
+    testing.expectEqual(true, mark1 instanceof PerformanceMark);
+    testing.expectEqual('start', mark1.name);
+    testing.expectEqual('mark', mark1.entryType);
+    testing.expectEqual(0, mark1.duration);
+    testing.expectEqual(null, mark1.detail);
+
+    let mark2 = performance.mark("start", {startTime: 32939393.9});
+    testing.expectEqual(32939393.9, mark2.startTime);
+  }
+</script>
+
+<script id=getEntries>
+  {
+    // Clear any existing marks first
+    performance.clearMarks();
+
+    const entries1 = performance.getEntries();
+    const initialCount = entries1.length;
+
+    performance.mark("test1");
+    performance.mark("test2");
+    performance.mark("test3");
+
+    const entries2 = performance.getEntries();
+    testing.expectEqual(initialCount + 3, entries2.length);
+  }
+</script>
+
+<script id=getEntriesByType>
+  {
+    performance.clearMarks();
+
+    performance.mark("mark1");
+    performance.mark("mark2");
+
+    const marks = performance.getEntriesByType("mark");
+    testing.expectEqual(2, marks.length);
+    testing.expectEqual('mark1', marks[0].name);
+    testing.expectEqual('mark2', marks[1].name);
+  }
+</script>
+
+<script id=getEntriesByName>
+  {
+    performance.clearMarks();
+
+    performance.mark("myMark");
+    performance.mark("otherMark");
+    performance.mark("myMark");
+
+    const entries = performance.getEntriesByName("myMark");
+    testing.expectEqual(2, entries.length);
+    testing.expectEqual('myMark', entries[0].name);
+    testing.expectEqual('myMark', entries[1].name);
+
+    const byType = performance.getEntriesByName("myMark", "mark");
+    testing.expectEqual(2, byType.length);
+  }
+</script>
+
+<script id=clearMarks>
+  {
+    performance.clearMarks();
+
+    performance.mark("mark1");
+    performance.mark("mark2");
+    performance.mark("mark3");
+
+    let marks = performance.getEntriesByType("mark");
+    testing.expectEqual(3, marks.length);
+
+    // Clear specific mark
+    performance.clearMarks("mark2");
+    marks = performance.getEntriesByType("mark");
+    testing.expectEqual(2, marks.length);
+    testing.expectEqual('mark1', marks[0].name);
+    testing.expectEqual('mark3', marks[1].name);
+
+    // Clear all marks
+    performance.clearMarks();
+    marks = performance.getEntriesByType("mark");
+    testing.expectEqual(0, marks.length);
+  }
+</script>
diff --git a/src/browser/webapi/Performance.zig b/src/browser/webapi/Performance.zig
index c659a7f8..e272f71a 100644
--- a/src/browser/webapi/Performance.zig
+++ b/src/browser/webapi/Performance.zig
@@ -1,20 +1,22 @@
 const js = @import("../js/js.zig");
+const Page = @import("../Page.zig");
 const datetime = @import("../../datetime.zig");
 
 pub fn registerTypes() []const type {
-    return &.{
-        Performance,
-        Entry,
-    };
+    return &.{ Performance, Entry, Mark };
 }
 
+const std = @import("std");
+
 const Performance = @This();
 
 _time_origin: u64,
+_entries: std.ArrayListUnmanaged(*Entry) = .{},
 
 pub fn init() Performance {
     return .{
         ._time_origin = datetime.milliTimestamp(.monotonic),
+        ._entries = .{},
     };
 }
 
@@ -28,6 +30,75 @@ pub fn getTimeOrigin(self: *const Performance) f64 {
     return @floatFromInt(self._time_origin);
 }
 
+pub fn mark(self: *Performance, name: []const u8, _options: ?Mark.Options, page: *Page) !*Mark {
+    const m = try Mark.init(name, _options, page);
+    try self._entries.append(page.arena, m._proto);
+    return m;
+}
+
+pub fn clearMarks(self: *Performance, mark_name: ?[]const u8) void {
+    if (mark_name) |name| {
+        // Remove specific mark by name
+        var i: usize = 0;
+        while (i < self._entries.items.len) {
+            const entry = self._entries.items[i];
+            if (entry._type == .mark and std.mem.eql(u8, entry._name, name)) {
+                _ = self._entries.orderedRemove(i);
+            } else {
+                i += 1;
+            }
+        }
+    } else {
+        // Remove all marks
+        var i: usize = 0;
+        while (i < self._entries.items.len) {
+            const entry = self._entries.items[i];
+            if (entry._type == .mark) {
+                _ = self._entries.orderedRemove(i);
+            } else {
+                i += 1;
+            }
+        }
+    }
+}
+
+pub fn getEntries(self: *const Performance) []*Entry {
+    return self._entries.items;
+}
+
+pub fn getEntriesByType(self: *const Performance, entry_type: []const u8, page: *Page) ![]const *Entry {
+    var result: std.ArrayList(*Entry) = .empty;
+
+    for (self._entries.items) |entry| {
+        if (std.mem.eql(u8, entry.getEntryType(), entry_type)) {
+            try result.append(page.call_arena, entry);
+        }
+    }
+
+    return result.items;
+}
+
+pub fn getEntriesByName(self: *const Performance, name: []const u8, entry_type: ?[]const u8, page: *Page) ![]const *Entry {
+    var result: std.ArrayList(*Entry) = .empty;
+
+    for (self._entries.items) |entry| {
+        if (!std.mem.eql(u8, entry._name, name)) {
+            continue;
+        }
+
+        const et = entry_type orelse {
+            try result.append(page.call_arena, entry);
+            continue;
+        };
+
+        if (std.mem.eql(u8, entry.getEntryType(), et)) {
+            try result.append(page.call_arena, entry);
+        }
+    }
+
+    return result.items;
+}
+
 pub const JsApi = struct {
     pub const bridge = js.Bridge(Performance);
 
@@ -38,16 +109,21 @@ pub const JsApi = struct {
     };
 
     pub const now = bridge.function(Performance.now, .{});
+    pub const mark = bridge.function(Performance.mark, .{});
+    pub const clearMarks = bridge.function(Performance.clearMarks, .{});
+    pub const getEntries = bridge.function(Performance.getEntries, .{});
+    pub const getEntriesByType = bridge.function(Performance.getEntriesByType, .{});
+    pub const getEntriesByName = bridge.function(Performance.getEntriesByName, .{});
     pub const timeOrigin = bridge.accessor(Performance.getTimeOrigin, null, .{});
 };
 
 pub const Entry = struct {
     _duration: f64 = 0.0,
-    _entry_type: Type,
+    _type: Type,
     _name: []const u8,
     _start_time: f64 = 0.0,
 
-    const Type = enum {
+    const Type = union(enum) {
         element,
         event,
         first_input,
@@ -55,13 +131,13 @@ pub const Entry = struct {
         layout_shift,
         long_animation_frame,
         longtask,
-        mark,
         measure,
         navigation,
         paint,
         resource,
         taskattribution,
         visibility_state,
+        mark: *Mark,
     };
 
     pub fn getDuration(self: *const Entry) f64 {
@@ -69,7 +145,7 @@ pub const Entry = struct {
     }
 
     pub fn getEntryType(self: *const Entry) []const u8 {
-        return switch (self._entry_type) {
+        return switch (self._type) {
             .first_input => "first-input",
             .largest_contentful_paint => "largest-contentful-paint",
             .layout_shift => "layout-shift",
@@ -95,8 +171,58 @@ pub const Entry = struct {
             pub const prototype_chain = bridge.prototypeChain();
             pub var class_id: bridge.ClassId = undefined;
         };
+        pub const name = bridge.accessor(Entry.getName, null, .{});
         pub const duration = bridge.accessor(Entry.getDuration, null, .{});
         pub const entryType = bridge.accessor(Entry.getEntryType, null, .{});
+        pub const startTime = bridge.accessor(Entry.getStartTime, null, .{});
+    };
+};
+
+pub const Mark = struct {
+    _proto: *Entry,
+    _detail: ?js.Object,
+
+    const Options = struct {
+        detail: ?js.Object = null,
+        startTime: ?f64 = null,
+    };
+
+    pub fn init(name: []const u8, _opts: ?Options, page: *Page) !*Mark {
+        const opts = _opts orelse Options{};
+        const start_time = opts.startTime orelse page.window._performance.now();
+
+        if (start_time < 0.0) {
+            return error.TypeError;
+        }
+
+        const detail = if (opts.detail) |d| try d.persist() else null;
+        const m = try page._factory.create(Mark{
+            ._proto = undefined,
+            ._detail = detail,
+        });
+
+        const entry = try page._factory.create(Entry{
+            ._start_time = start_time,
+            ._name = try page.dupeString(name),
+            ._type = .{ .mark = m },
+        });
+        m._proto = entry;
+        return m;
+    }
+
+    pub fn getDetail(self: *const Mark) ?js.Object {
+        return self._detail;
+    }
+
+    pub const JsApi = struct {
+        pub const bridge = js.Bridge(Mark);
+
+        pub const Meta = struct {
+            pub const name = "PerformanceMark";
+            pub const prototype_chain = bridge.prototypeChain();
+            pub var class_id: bridge.ClassId = undefined;
+        };
+        pub const detail = bridge.accessor(Mark.getDetail, null, .{});
     };
 };