Add E-Signatures to Bun

Quick start

1. Get an API key from signb.ee (free, no credit card)
2. Set SIGNBEE_API_KEY in your environment
3. Add the code below to your app

Bun example

Bun.serve({
  port: 3000,
  async fetch(req) {
    if (req.method !== "POST") return new Response("Not found", { status: 404 });
    const body = await req.json();
    const res = await fetch("https://signb.ee/api/send", {
      method: "POST",
      headers: {
        Authorization: `Bearer ${Bun.env.SIGNBEE_API_KEY}`,
        "Content-Type": "application/json",
      },
      body: JSON.stringify(body),
    });
    return new Response(await res.text(), {
      headers: { "Content-Type": "application/json" },
    });
  },
});

What happens

1. Your app sends markdown or a PDF URL to Signbee
2. Signbee generates a PDF (if markdown) and emails the recipient a signing link
3. Recipient signs — both parties receive the signed PDF with SHA-256 certificate

Also works with AI agents

Install the MCP server to let Claude, Cursor, or Windsurf send documents directly:

npx -y signbee-mcp

Integration details

Bun is the fastest JavaScript runtime, designed as a drop-in Node.js replacement with native TypeScript support, a built-in bundler, and a built-in HTTP server. Adding e-signatures to Bun is nearly identical to Deno — built-in fetch, built-in server, zero dependencies.

Performance: Bun's HTTP server handles significantly more requests per second than Node.js. For high-volume contract signing services, Bun provides the best JavaScript runtime performance without code changes.

Bun.env: Access environment variables via Bun.env.SIGNBEE_API_KEY (shown in the example). Bun automatically loads .env files without dotenv. This simplifies development setup compared to Node.js.

Node.js compatibility: Bun is designed as a Node.js drop-in replacement. Your existing Express, Fastify, or Hono code runs on Bun without modifications. The example shows Bun's native server, but any Node.js framework works too.

Bun.build: Use Bun's built-in bundler for production builds. This eliminates the need for webpack, esbuild, or rollup in your toolchain. A single bun build command produces an optimised production bundle.

Package management: Bun's package manager is the fastest available. Install dependencies with bun install (10-100x faster than npm). Lock file format is compatible with npm for team environments.

FAQs