diff --git a/.github/ISSUE_TEMPLATE/dev_zig_nomination.md b/.github/ISSUE_TEMPLATE/dev_zig_nomination.md
index 2013e7ad..10dc05cd 100644
--- a/.github/ISSUE_TEMPLATE/dev_zig_nomination.md
+++ b/.github/ISSUE_TEMPLATE/dev_zig_nomination.md
@@ -44,7 +44,6 @@ You may have been linked to this issue because you sent a pull request to update
 
 These projects have zero `build.zig.zon` dependencies, we update them first - and in any order.
 
-* [ ] mach-sysjs
 * [ ] mach-objc-generator
 * [ ] fastfilter
 * [ ] spirv-cross
@@ -122,7 +121,6 @@ These projects have dependencies on other projects. We update them in the exact
   * mach-basisu
   * mach-freetype
   * font-assets
-  * mach-sysjs
   * mach-gpu
   * mach-glfw
   * mach-objc
diff --git a/build.zig b/build.zig
index bd7664d5..648c8813 100644
--- a/build.zig
+++ b/build.zig
@@ -78,13 +78,6 @@ pub fn build(b: *std.Build) !void {
     });
     module.addImport("build-options", build_options.createModule());
 
-    if ((want_mach or want_core or want_sysaudio) and target.result.cpu.arch == .wasm32) {
-        if (b.lazyDependency("mach_sysjs", .{
-            .target = target,
-            .optimize = optimize,
-        })) |dep| module.addImport("mach-sysjs", dep.module("mach-sysjs"));
-    }
-
     if (want_mach) {
         // Linux gamemode requires libc.
         if (target.result.os.tag == .linux) module.link_libc = true;
@@ -434,7 +427,7 @@ pub const CoreApp = struct {
             }
         }
         if (platform == .web) {
-            inline for (.{ sdkPath("/src/core/platform/wasm/mach.js"), @import("mach_sysjs").getJSPath() }) |js| {
+            inline for (.{ sdkPath("/src/core/platform/wasm/mach.js"), sdkPath("/src/sysjs/mach-sysjs.js") }) |js| {
                 const install_js = app_builder.addInstallFileWithDir(
                     .{ .path = js },
                     std.Build.InstallDir{ .custom = "www" },
diff --git a/build.zig.zon b/build.zig.zon
index 0adb06f4..27fd6a11 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -32,12 +32,6 @@
             .hash = "12205a32c8e6ca23c68191b1e95405d2bd5f8e3055cba1c8ce0738d673ef49aef913",
             .lazy = true,
         },
-        .mach_sysjs = .{
-            .url = "https://pkg.machengine.org/mach-sysjs/eeef024f79beae189b7a4ed85e64ed076e76d538.tar.gz",
-            .hash = "1220db6845ce34743ae2a1ab0222efc942496adde2736c20e3443d4fde4ef64b11b9",
-            // TODO(build): be able to mark this dependency as lazy
-            // .lazy = true,
-        },
         .mach_objc = .{
             .url = "https://pkg.machengine.org/mach-objc/a7c3483702998aa0e960a788b9f611389f17d402.tar.gz",
             .hash = "1220049052fca861248fa6fb8bc24ecdb038049be0a3b22352bebc40e4dc2d2c981b",
diff --git a/src/sysjs/mach-sysjs.js b/src/sysjs/mach-sysjs.js
new file mode 100644
index 00000000..cabeac40
--- /dev/null
+++ b/src/sysjs/mach-sysjs.js
@@ -0,0 +1,366 @@
+let text_decoder = new TextDecoder();
+let text_encoder = new TextEncoder();
+let log_buf = "";
+
+let uindex = 0;
+let indices = [];
+let values = [];
+let value_map = {};
+
+class MemoryBlock {
+  constructor(mem, offset = 0) {
+    this.mem = mem;
+    this.offset = offset;
+  }
+
+  slice(offset) {
+    return new MemoryBlock(this.mem, offset);
+  }
+
+  getMemory() {
+    return new DataView(this.mem, this.offset);
+  }
+
+  getU8(offset) {
+    return this.getMemory().getUint8(offset, true);
+  }
+
+  getU32(offset) {
+    return this.getMemory().getUint32(offset, true);
+  }
+
+  getU64(offset) {
+    const ls = this.getU32(offset);
+    const ms = this.getU32(offset + 4);
+
+    return ls + ms * 4294967296;
+  }
+
+  getF64(offset) {
+    return this.getMemory().getFloat64(offset, true);
+  }
+
+  getSlice(offset, len) {
+    return new Uint8Array(this.mem, offset, len);
+  }
+
+  getString(offset, len) {
+    return text_decoder.decode(new Uint8Array(this.mem, offset, len));
+  }
+
+  setU8(offset, data) {
+    this.getMemory().setUint8(offset, data, true);
+  }
+
+  setU32(offset, data) {
+    this.getMemory().setUint32(offset, data, true);
+  }
+
+  setU64(offset, data) {
+    this.getMemory().setUint32(offset, data, true);
+    this.getMemory().setUint32(offset + 4, Math.floor(data / 4294967296), true);
+  }
+
+  setF64(offset, data) {
+    this.getMemory().setFloat64(offset, data, true);
+  }
+
+  setString(offset, str) {
+    const string = text_encoder.encode(str);
+    const buffer = new Uint8Array(this.mem, offset, string.length);
+    for (let i = 0; i < string.length; i += 1) {
+      buffer[i] = string[i];
+    }
+  }
+}
+
+const sysjs = {
+  wasm: undefined,
+  buffer: undefined,
+
+  init(wasm) {
+    this.wasm = wasm;
+
+    values = [];
+    value_map = {};
+    this.addValue(globalThis);
+  },
+
+  addValue(value) {
+    value.__proto__.__uindex = uindex;
+    let idx = indices.pop();
+    if (idx !== undefined) {
+      values[idx] = value;
+    } else {
+      idx = values.push(value) - 1;
+    }
+    value_map[uindex] = idx;
+    uindex += 1;
+    return idx;
+  },
+
+  zigCreateMap() {
+    return sysjs.addValue(new Map());
+  },
+
+  zigCreateArray() {
+    return sysjs.addValue(new Array());
+  },
+
+  zigCreateString(str, len) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    return sysjs.addValue(memory.getString(str, len));
+  },
+
+  zigCreateFunction(id, captures, len) {
+    return sysjs.addValue(function () {
+      const args = sysjs.addValue(arguments);
+      sysjs.wasm.exports.wasmCallFunction(id, args, arguments.length, captures, len);
+      const return_value = values[args]["return_value"];
+      sysjs.zigCleanupObject(args);
+      return return_value;
+    });
+  },
+
+  getType(value) {
+    switch (typeof value) {
+      case "object":
+        switch (value) {
+          case null:
+            return 4;
+          default:
+            return 0;
+        }
+      case "number":
+        return 1;
+      case "boolean":
+        return 2;
+      case "string":
+        return 3;
+      case "undefined":
+        return 5;
+      case "function":
+        return 6;
+    }
+  },
+
+  writeObject(block, data, type) {
+    switch (type) {
+      case 0:
+      case 6:
+        block.setU8(0, type);
+        block.setU64(8, data);
+        break;
+      case 1:
+        block.setU8(0, 1);
+        block.setF64(8, data);
+        break;
+      case 2:
+        block.setU8(0, 2);
+        block.setU8(8, data);
+        break;
+      case 3:
+        block.setU8(0, 3);
+        block.setU64(8, data);
+        break;
+      case 4:
+        block.setU8(0, 4);
+        break;
+      case 5:
+        block.setU8(0, 5);
+        break;
+    }
+  },
+
+  readObject(block) {
+    switch (block.getU8(0)) {
+      case 0:
+      case 6:
+        return values[block.getU64(8)];
+      case 1:
+        return block.getF64(8);
+      case 2:
+        return Boolean(block.getU8(8));
+      case 3:
+        return values[block.getU64(8)];
+      case 4:
+        return null;
+      case 5:
+        return undefined;
+    }
+  },
+
+  getPropertyEx(prop, ret_ptr, offset) {
+    let len = undefined;
+    const type = this.getType(prop);
+    switch (type) {
+      case 3:
+        len = prop.length;
+      case 0:
+      case 6:
+        if (prop in value_map) {
+          prop = value_map[prop.__uindex];
+        } else {
+          prop = sysjs.addValue(prop);
+        }
+        break;
+    }
+
+    if (len !== undefined) prop.__proto__.length = len;
+
+    let memory = new MemoryBlock(ret_ptr, offset);
+    sysjs.writeObject(memory, prop, type);
+  },
+
+  getProperty(prop, ret_ptr) {
+    return sysjs.getPropertyEx(prop, sysjs.wasm.exports.memory.buffer, ret_ptr);
+  },
+
+  zigGetProperty(id, name, len, ret_ptr) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    let prop = values[id][memory.getString(name, len)];
+    sysjs.getProperty(prop, ret_ptr);
+  },
+
+  zigSetProperty(id, name, len, set_ptr) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    values[id][memory.getString(name, len)] = sysjs.readObject(
+      memory.slice(set_ptr)
+    );
+  },
+
+  zigDeleteProperty(id, name, len) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    delete values[id][memory.getString(name, len)];
+  },
+
+  zigGetIndex(id, index, ret_ptr) {
+    let prop = values[id][index];
+    sysjs.getProperty(prop, ret_ptr);
+  },
+
+  zigSetIndex(id, index, set_ptr) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    values[id][index] = sysjs.readObject(memory.slice(set_ptr));
+  },
+
+  zigDeleteIndex(id, index) {
+    delete values[id][index];
+  },
+
+  zigCopyBytes(id, bytes, expected_length) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    const array = values[id];
+    if (array.length != expected_length) {
+      throw Error("copyBytes given array of length " + expected_length + " but destination has length " + array.length);
+    }
+    const slice = memory.getSlice(bytes, array.length);
+    array.set(slice);
+  },
+
+  zigGetAttributeCount(id) {
+    let obj = values[id];
+    return Object.keys(obj).length;
+  },
+
+  zigCleanupObject(id) {
+    const idx = Number(id);
+    delete value_map[values[idx].__uindex];
+    delete values[idx];
+    indices.push(idx);
+  },
+
+  zigGetStringLength(val_id) {
+    return values[value_map[val_id]].length;
+  },
+
+  zigGetString(val_id, ptr) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    memory.setString(ptr, values[value_map[val_id]]);
+  },
+
+  zigValueEqual(val, other) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    const val_js = sysjs.readObject(memory.slice(val));
+    const other_js = sysjs.readObject(memory.slice(other));
+    return val_js === other_js;
+  },
+
+  zigValueInstanceOf(val, other) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    const val_js = sysjs.readObject(memory.slice(val));
+    const other_js = sysjs.readObject(memory.slice(other));
+    return val_js instanceof other_js;
+  },
+
+  functionCall(func, this_param, args, args_len, ret_ptr) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    let argv = [];
+    for (let i = 0; i < args_len; i += 1) {
+      argv.push(sysjs.readObject(memory.slice(args + i * 16)));
+    }
+
+    let result = func.apply(this_param, argv);
+
+    let length = undefined;
+    const type = sysjs.getType(result);
+    switch (type) {
+      case 3:
+        length = result.length;
+      case 0:
+      case 6:
+        result = sysjs.addValue(result);
+        break;
+    }
+
+    if (length !== undefined) result.__proto__.length = length;
+
+    sysjs.writeObject(memory.slice(ret_ptr), result, type);
+  },
+
+  zigFunctionCall(id, name, len, args, args_len, ret_ptr) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    sysjs.functionCall(
+      values[id][memory.getString(name, len)],
+      values[id],
+      args,
+      args_len,
+      ret_ptr
+    );
+  },
+
+  zigFunctionInvoke(id, args, args_len, ret_ptr) {
+    sysjs.functionCall(values[id], undefined, args, args_len, ret_ptr);
+  },
+
+  zigGetParamCount(id) {
+    return values[id].length;
+  },
+
+  zigConstructType(id, args, args_len) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    let argv = [];
+    for (let i = 0; i < args_len; i += 1) {
+      argv.push(sysjs.readObject(memory.slice(args + i * 16)));
+    }
+
+    return sysjs.addValue(new values[id](...argv));
+  },
+
+  wzLogWrite(str, len) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    log_buf += memory.getString(str, len);
+  },
+
+  wzLogFlush() {
+    console.log(log_buf);
+    log_buf = "";
+  },
+
+  wzPanic(str, len) {
+    let memory = new MemoryBlock(sysjs.wasm.exports.memory.buffer);
+    throw Error(memory.getString(str, len));
+  },
+};
+
+export { sysjs };
diff --git a/src/sysjs/main.zig b/src/sysjs/main.zig
new file mode 100644
index 00000000..a0cdb9d7
--- /dev/null
+++ b/src/sysjs/main.zig
@@ -0,0 +1,269 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const builtin = @import("builtin");
+
+const js = struct {
+    extern "sysjs" fn zigCreateMap() u32;
+    extern "sysjs" fn zigCreateArray() u32;
+    extern "sysjs" fn zigCreateString(str: [*]const u8, len: u32) u32;
+    extern "sysjs" fn zigCreateFunction(id: *const anyopaque, captures: [*]Value, len: u32) u32;
+    extern "sysjs" fn zigGetAttributeCount(id: u64) u32;
+    extern "sysjs" fn zigGetProperty(id: u64, name: [*]const u8, len: u32, ret_ptr: *anyopaque) void;
+    extern "sysjs" fn zigSetProperty(id: u64, name: [*]const u8, len: u32, set_ptr: *const anyopaque) void;
+    extern "sysjs" fn zigDeleteProperty(id: u64, name: [*]const u8, len: u32) void;
+    extern "sysjs" fn zigGetIndex(id: u64, index: u32, ret_ptr: *anyopaque) void;
+    extern "sysjs" fn zigSetIndex(id: u64, index: u32, set_ptr: *const anyopaque) void;
+    extern "sysjs" fn zigGetString(val_id: u64, ptr: [*]const u8) void;
+    extern "sysjs" fn zigGetStringLength(val_id: u64) u32;
+    extern "sysjs" fn zigValueEqual(val: *const anyopaque, other: *const anyopaque) bool;
+    extern "sysjs" fn zigValueInstanceOf(val: *const anyopaque, other: *const anyopaque) bool;
+    extern "sysjs" fn zigDeleteIndex(id: u64, index: u32) void;
+    extern "sysjs" fn zigCopyBytes(id: u64, bytes: [*]u8, expected_len: u32) void;
+    extern "sysjs" fn zigFunctionCall(id: u64, name: [*]const u8, len: u32, args: ?*const anyopaque, args_len: u32, ret_ptr: *anyopaque) void;
+    extern "sysjs" fn zigFunctionInvoke(id: u64, args: ?*const anyopaque, args_len: u32, ret_ptr: *anyopaque) void;
+    extern "sysjs" fn zigGetParamCount(id: u64) u32;
+    extern "sysjs" fn zigConstructType(id: u64, args: ?*const anyopaque, args_len: u32) u32;
+    extern "sysjs" fn zigCleanupObject(id: u64) void;
+};
+
+pub const Value = extern struct {
+    tag: Tag,
+    val: extern union {
+        ref: u64,
+        num: f64,
+        bool: bool,
+    },
+
+    pub const Tag = enum(u8) {
+        object,
+        num,
+        bool,
+        str,
+        null,
+        undefined,
+        func,
+    };
+
+    pub fn is(val: *const Value, comptime tag: Tag) bool {
+        return val.tag == tag;
+    }
+
+    pub fn view(val: *const Value, comptime tag: Tag) switch (tag) {
+        .object => Object,
+        .num => f64,
+        .bool => bool,
+        .str => String,
+        .func => Function,
+        .null, .undefined => @compileError("Cannot get null or undefined as a value"),
+    } {
+        return switch (tag) {
+            .object => Object{ .ref = val.val.ref },
+            .num => val.val.num,
+            .bool => val.val.bool,
+            .str => String{ .ref = val.val.ref },
+            .func => Function{ .ref = val.val.ref },
+            else => unreachable,
+        };
+    }
+
+    pub fn eql(val: *const Value, other: Value) bool {
+        if (val.tag != other.tag)
+            return false;
+
+        return switch (val.tag) {
+            .num => val.val.num == other.val.num,
+            .bool => val.val.bool == other.val.bool,
+            // Using JS equality (===) is better here since lets say a ref can be dangling
+            else => js.zigValueEqual(val, &other),
+        };
+    }
+
+    pub fn instanceOf(val: *const Value, other: Value) bool {
+        return js.zigValueInstanceOf(val, &other);
+    }
+
+    pub fn format(val: *const Value, comptime _: []const u8, _: std.fmt.FormatOptions, writer: anytype) !void {
+        switch (val.tag) {
+            .object => try writer.print("Object@{}({})", .{ val.val.ref, val.view(.object).attributeCount() }),
+            .num => if (val.val.num > 10000)
+                try writer.print("{e}", .{val.val.num})
+            else
+                try writer.print("{d}", .{val.val.num}),
+            .bool => try writer.writeAll(if (val.view(.bool)) "true" else "false"),
+            .str => try writer.print("String@{}({})", .{ val.val.ref, val.view(.str).getLength() }),
+            .func => try writer.print("Function@{}({})", .{ val.val.ref, val.view(.func).paramCount() }),
+            .null => try writer.writeAll("null"),
+            .undefined => try writer.writeAll("undefined"),
+        }
+    }
+};
+
+pub const Object = struct {
+    ref: u64,
+
+    pub fn deinit(obj: *const Object) void {
+        js.zigCleanupObject(obj.ref);
+    }
+
+    pub fn toValue(obj: *const Object) Value {
+        return .{ .tag = .object, .val = .{ .ref = obj.ref } };
+    }
+
+    pub fn attributeCount(obj: *const Object) usize {
+        return js.zigGetAttributeCount(obj.ref);
+    }
+
+    pub fn get(obj: *const Object, prop: []const u8) Value {
+        var ret: Value = undefined;
+        js.zigGetProperty(obj.ref, prop.ptr, @as(u32, @intCast(prop.len)), &ret);
+        return ret;
+    }
+
+    pub fn set(obj: *const Object, prop: []const u8, value: Value) void {
+        js.zigSetProperty(obj.ref, prop.ptr, @as(u32, @intCast(prop.len)), &value);
+    }
+
+    pub fn delete(obj: *const Object, prop: []const u8) void {
+        js.zigDeleteProperty(obj.ref, prop.ptr, @as(u32, @intCast(prop.len)));
+    }
+
+    pub fn getIndex(obj: *const Object, index: u32) Value {
+        var ret: Value = undefined;
+        js.zigGetIndex(obj.ref, index, &ret);
+        return ret;
+    }
+
+    pub fn setIndex(obj: *const Object, index: u32, value: Value) void {
+        js.zigSetIndex(obj.ref, index, &value);
+    }
+
+    pub fn deleteIndex(obj: *const Object, index: u32) void {
+        js.zigDeleteIndex(obj.ref, index);
+    }
+
+    pub fn copyBytes(obj: *const Object, bytes: []u8) void {
+        js.zigCopyBytes(obj.ref, bytes.ptr, @as(u32, @intCast(bytes.len)));
+    }
+
+    pub fn call(obj: *const Object, fun: []const u8, args: []const Value) Value {
+        var ret: Value = undefined;
+        js.zigFunctionCall(obj.ref, fun.ptr, @as(u32, @intCast(fun.len)), args.ptr, @as(u32, @intCast(args.len)), &ret);
+        return ret;
+    }
+};
+
+pub const Function = struct {
+    ref: u64,
+
+    pub fn deinit(func: *const Function) void {
+        js.zigCleanupObject(func.ref);
+    }
+
+    pub fn toValue(func: *const Function) Value {
+        return .{ .tag = .func, .val = .{ .ref = func.ref } };
+    }
+
+    pub fn paramCount(func: *const Function) usize {
+        // FIXME: native functions would always return 0
+        return js.zigGetParamCount(func.ref);
+    }
+
+    pub fn construct(func: *const Function, args: []const Value) Object {
+        return .{ .ref = js.zigConstructType(func.ref, args.ptr, @as(u32, @intCast(args.len))) };
+    }
+
+    pub fn invoke(func: *const Function, args: []const Value) Value {
+        var ret: Value = undefined;
+        js.zigFunctionInvoke(func.ref, args.ptr, @as(u32, @intCast(args.len)), &ret);
+        return ret;
+    }
+};
+
+pub const String = struct {
+    ref: u64,
+
+    pub fn deinit(string: *const String) void {
+        js.zigCleanupObject(string.ref);
+    }
+
+    pub fn toValue(string: *const String) Value {
+        return .{ .tag = .str, .val = .{ .ref = string.ref } };
+    }
+
+    pub fn getLength(string: *const String) usize {
+        return js.zigGetStringLength(string.ref);
+    }
+
+    pub fn getOwnedSlice(string: *const String, allocator: std.mem.Allocator) ![]const u8 {
+        const slice = try allocator.alloc(u8, string.getLength());
+        errdefer allocator.free(slice);
+        js.zigGetString(string.ref, slice.ptr);
+        return slice;
+    }
+};
+
+export fn wasmCallFunction(id: *anyopaque, args: u32, len: u32, captures: [*]Value, captures_len: u32) void {
+    var captures_slice: []Value = undefined;
+    captures_slice.ptr = captures;
+    captures_slice.len = captures_len;
+
+    const obj = Object{ .ref = args };
+    const func = @as(FunType, @ptrCast(@alignCast(id)));
+    obj.set("return_value", func(obj, len, captures_slice));
+}
+
+pub fn global() Object {
+    return Object{ .ref = 0 };
+}
+
+pub fn createMap() Object {
+    return .{ .ref = js.zigCreateMap() };
+}
+
+pub fn createArray() Object {
+    return .{ .ref = js.zigCreateArray() };
+}
+
+pub fn createString(string: []const u8) String {
+    return .{ .ref = js.zigCreateString(string.ptr, @as(u32, @intCast(string.len))) };
+}
+
+pub fn createNumber(num: anytype) Value {
+    switch (@typeInfo(@TypeOf(num))) {
+        .Int,
+        .Float,
+        .ComptimeInt,
+        .ComptimeFloat,
+        => return .{ .tag = .num, .val = .{ .num = std.math.lossyCast(f64, num) } },
+        else => @compileError("expected integer, found " ++ @typeName(@TypeOf(num))),
+    }
+}
+
+pub fn createBool(val: bool) Value {
+    return .{ .tag = .bool, .val = .{ .bool = val } };
+}
+
+pub fn createNull() Value {
+    return .{ .tag = .null, .val = undefined };
+}
+
+pub fn createUndefined() Value {
+    return .{ .tag = .undefined, .val = undefined };
+}
+
+const FunType = *const fn (args: Object, args_len: u32, captures: []Value) Value;
+
+pub fn createFunction(fun: FunType, captures: []Value) Function {
+    return .{ .ref = js.zigCreateFunction(fun, captures.ptr, @as(u32, @intCast(captures.len))) };
+}
+
+pub fn constructType(t: []const u8, args: []const Value) Object {
+    const constructor = global().get(t).view(.func);
+    defer constructor.deinit();
+
+    return constructor.construct(args);
+}
+
+test {
+    std.testing.refAllDeclsRecursive(@This());
+}