N64 Wasm May 2026

N64 WASM: Running GoldenEye and Mario 64 Natively in Your Browser

It started as a fever dream in the early 2010s: "What if you could play Super Mario 64 in a browser tab without plugins?" Back then, the answer was Java applets or clunky Flash wrappers—both slow, insecure, and unreliable. Fast forward to today, and the landscape has changed entirely. WebAssembly (WASM) has turned the browser into a legitimate gaming powerhouse, and the Nintendo 64—one of the most architecturally complex consoles of the 90s—is now running at full speed on desktops, tablets, and even high-end phones, all within a <canvas> tag.

This is the story of N64 WASM: the technology, the performance challenges, the legal gray areas, and where this is all heading. n64 wasm

Performance tips

• Batch JS/WASM interactions: send aggregated input or audio frames instead of many small calls.
• Use TypedArray views for shared buffers to avoid copying.
• Prefer WebGL draw calls with textures for video rather than per-pixel operations in JS.
• Use requestAnimationFrame for display timing and AudioWorklet for audio timing.

1. SharedArrayBuffer and Threads

WASM now supports real multithreading via SharedArrayBuffer. This allows the N64 emulator to run the CPU in one thread, the RDP in another, and the audio in a third—exactly as native emulators do. Firefox and Chrome have re-enabled this (with COOP/COEP headers). Expect a 2x speed boost for heavy games like Perfect Dark. N64 WASM: Running GoldenEye and Mario 64 Natively

2. JavaScript Glue Code (main.js)

This code bridges the gap between the user's browser and the WASM binary. It enables downloading the save state as a file. Batch JS/WASM interactions: send aggregated input or audio

// Assuming 'Module' is the Emscripten runtime object
const Module = window.Module;
/**
 * Triggers a download of the current emulator state.
 */
function downloadSaveState() 
    try 
        // 1. Call the C function to get size
        let sizePtr = Module._malloc(4); // Allocate space for size_t
        let bufferPtr = Module.ccall(
            'emulator_get_snapshot_data', 
            'number', 
            ['number'], 
            [sizePtr]
        );
if (!bufferPtr) 
            console.error("Failed to get snapshot data!");
            Module._free(sizePtr);
            return;
// 2. Read the size from memory
        let size = Module.getValue(sizePtr, 'i32');
// 3. Copy data from WASM heap to a JS Array
        let data = Module.HEAPU8.subarray(bufferPtr, bufferPtr + size);
// 4. Create a Blob and trigger download
        let blob = new Blob([data],  type: 'application/octet-stream' );
        let url = URL.createObjectURL(blob);
let a = document.createElement('a');
        a.href = url;
        a.download = 'n64_snapshot.state'; // File extension
        document.body.appendChild(a);
        a.click();
// 5. Cleanup
        setTimeout(() => 
            document.body.removeChild(a);
            URL.revokeObjectURL(url);
            Module.ccall('emulator_free_buffer', 'void', ['number'], [bufferPtr]);
            Module._free(sizePtr);
        , 100);
console.log("Save state downloaded successfully! Size: " + size + " bytes");
catch (e) 
        console.error("Error saving state:", e);
/**
 * Loads a save state from a file input.
 * @param File file 
 */
function uploadSaveState(file) 
    let reader = new FileReader();
    reader.onload = function(e) 
        let arrayBuffer = e.target.result;
        let byteArray = new Uint8Array(arrayBuffer);
// 1. Allocate memory in WASM heap and copy data into it
        let ptr = Module._malloc(byteArray.length);
        Module.HEAPU8.set(byteArray, ptr);
// 2. Call the C function to load the state
        let result = Module.ccall(
            'emulator_load_snapshot_data', 
            'number', 
            ['number', 'number'], 
            [ptr, byteArray.length]
        );
// 3. Free the memory
        Module._free(ptr);
if (result === 0) 
            console.log("Save state loaded successfully!");
            // Optional: Force a frame redraw or unpause the emulator here
         else 
            console.error("Failed to load save state (Invalid file or version mismatch).");
;
    reader.readAsArrayBuffer(file);
// Export functions to be used by UI buttons
window.downloadSaveState = downloadSaveState;
window.uploadSaveState = uploadSaveState;