Vercel WebSockets Go GA After 300 Million Connections

Vercel made WebSocket support in Vercel Functions generally available Oct. 20, four months after opening a public beta. Apps can now hold open connections for chat, streaming and multiplayer features on a supported path (Vercel changelog, Oct. 20, 2026).

What Shipped

Vercel said its CDN has served 300 million WebSocket connections since the beta launched June 22, and now serves 15 million a day. Vercel named AI chat, streaming and realtime multiplayer apps as the main uses. It said WebSockets also power the realtime models in its AI Gateway.

Vercel said connections follow the same limits and pricing as other Function invocations. Under Active CPU pricing, CPU is billed only for the time spent processing messages. Vercel’s documentation lists WebSockets as available on all plans.

Setup needs no Vercel-specific configuration. Vercel’s docs show the ws library upgrading connections from a Node.js HTTP server exported from api/ws.ts, and say Socket.IO, Express, Hono, h3, Nitro and Bun’s native Bun.serve() API also work. Socket.IO clients must set transports: ['websocket']. The library defaults to HTTP long-polling.

What the Docs Say to Plan For

The documentation is more cautious than the changelog. Each connection is pinned to one function instance for its lifetime. New connections are not guaranteed to reach the same instance. Vercel tells developers to keep rooms, presence, counters and pub/sub state in an external store, and names Redis from its Marketplace as one option.

Connections close when a function reaches its maximum duration. Clients need reconnect logic that resubscribes and reloads state. The docs also say existing connections stay on the previous deployment after a new deploy until they close. The Bun path has listed gaps too: headers passed to server.upgrade() are not applied to the upgrade response, and the drain handler is not invoked.

The Take

The 15 million daily connections show demand. The docs describe a stateless fleet with sockets pinned to instances. A chat demo fits that model. A game room or collaborative editor needs an external store, plus a plan for the connection that dies when a function times out.

Vercel WebSockets suit simple fan-out. They do not replace coordination infrastructure.

Key Takeaways

• Vercel WebSocket support reached general availability Oct. 20, 2026.
• Vercel reported 300 million connections since the June 22 beta and 15 million a day now.
• Pricing and limits match other Function invocations, with CPU billed only while processing messages.
• Keep shared state outside the function. Handle reconnects when a connection closes.