wrangler dev supports raw socket connect triggers

Introduced 2026-08-20 · score 0.98

HOW TO USE IT

When configuring raw TCP connections for local development, enable the `experimental` compatibility flag and add a `connect` trigger; `wrangler dev` forwards connections to the Worker’s `connect(socket, env, ctx)` handler. [Release note](https://github.com/cloudflare/workers-sdk/releases/tag/wrangler%404.125.0)

{
  "compatibility_flags": ["experimental"],
  "connect": [{ "protocol": "tcp", "port": 5432 }]
}

import { defineWorker, triggers } from "@cloudflare/config";

export default defineWorker({
  triggers: [
    triggers.connect({ protocol: "tcp", port: 5432, address: "127.0.0.1" }),
  ],
});

npx wrangler dev

WHY THIS HELPS

Configure a Worker to handle raw TCP connections during local development.

REQUIREMENTS AND LIMITATIONS

Version: 4.125.0
compatibility_flags: "experimental" (required): Required compatibility flag for the connect trigger.
connect[].protocol (required): Protocol to listen for; only `"tcp"` is supported.
connect[].port (required): Port for the listening socket. The example uses `5432`.
connect[].address: Listening address; defaults to `127.0.0.1`.
triggers.connect(...): `@cloudflare/config` declaration that lowers to the `connect` field.
Requires the `experimental` compatibility flag.
Only `"tcp"` is supported at the moment.
Each entry listens on `127.0.0.1` unless an `address` is given.
Connections bypass the local dev HTTP entry point.

FIRST-PARTY EVIDENCE

Check the installed version and the source before using it. Entry JSON

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wrangler dev supports raw socket connect triggers