Canvas 2D — in a Worker

A complete HTML5 Canvas implementation that runs in a Cloudflare Worker, browser Web Worker, Vercel Edge function, or any V8 isolate that supports WASM-SIMD. Drop-in for code that already targets <canvas> or @napi-rs/canvas: Canvas, CanvasRenderingContext2D, Path2D, Image, ImageData, DOMMatrix, CanvasGradient, CanvasPattern. Spec divergences are listed in Compatibility.

@napi-rs/canvas and node-canvas need Node-API or Cairo; neither runs in a Worker. simdra ships as a single ~500 KB gzipped WASM bundle with NEON / SSE / WASM-SIMD code paths under the hood. Same Canvas API, no native deps, no postinstall.

Install

npm install simdra

For runtime-specific setup (Cloudflare Workers, Vercel Edge, Deno, Bun, browser bundlers, Web Workers), see Installation.

60-second drawing

import { createCanvas } from 'simdra';
import { writeFileSync } from 'node:fs';

const canvas = createCanvas(400, 300);
const ctx = canvas.getContext('2d');

ctx.fillStyle = '#03a9f4';
ctx.fillRect(0, 0, 400, 300);

ctx.fillStyle = '#ffffff';
ctx.font = '32px sans-serif';
ctx.fillText('Hello, simdra', 20, 80);

writeFileSync('hello.png', canvas.toBytes());
// JPEG: writeFileSync('hello.jpg', canvas.toBytes('image/jpeg', 0.9));

Read next

• Installation — Node, Cloudflare Workers, Vercel Edge, Deno, Bun, browser, Web Workers.
• API reference — drawing, paths, transforms, text, images, encoding.
• Compatibility — HTML5 spec coverage matrix.