Use Claude to Add Server-Sent Events to Your API

When you need real-time updates flowing from server to client — progress bars, live logs, notification feeds — Server-Sent Events (SSE) are simpler and more efficient than WebSockets for one-directional streams. Claude can wire them up in any framework.

Add a Server-Sent Events endpoint at /api/stream to our Express app. It should accept a job ID query param, stream progress events as the job runs, send a done event when complete, and clean up the connection if the client disconnects early.

Claude will generate the SSE handler with the correct Content-Type: text/event-stream headers, heartbeat pings to keep the connection alive through proxies, and proper cleanup logic tied to the req.on('close') event — the part developers most often forget.

On the frontend, Claude can generate the matching EventSource client:

// Claude generates this too
const source = new EventSource(`/api/stream?jobId=${jobId}`);
source.addEventListener('progress', (e) => updateUI(JSON.parse(e.data)));
source.addEventListener('done', () => source.close());

If you're on Next.js or a serverless runtime, ask Claude to use the ReadableStream + TransformStream pattern instead, which works across edge and serverless environments.

SSE is underused and underrated — Claude can add it in minutes.