Cloudflare Workers support the following protocols and interfaces:

| Protocol               | Inbound                                                                                                                                                                                                                                                                                                                                           | Outbound                                                                                                                                      |
| ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- |
| **HTTP / HTTPS**       | Handle incoming HTTP requests using the [`fetch()` handler](https://developers.cloudflare.com/workers/runtime-apis/handlers/fetch/)                                                                                                                                                                                                               | Make HTTP subrequests using the [`fetch()` API](https://developers.cloudflare.com/workers/runtime-apis/fetch/)                                |
| **Direct TCP sockets** | Support for handling inbound TCP connections is [coming soon](https://blog.cloudflare.com/workers-tcp-socket-api-connect-databases/)                                                                                                                                                                                                              | Create outbound TCP connections using the [`connect()` API](https://developers.cloudflare.com/workers/runtime-apis/tcp-sockets/)              |
| **WebSockets**         | Accept incoming WebSocket connections using the [`WebSocket` API](https://developers.cloudflare.com/workers/runtime-apis/websockets/), or with [MQTT over WebSockets (Pub/Sub)](https://developers.cloudflare.com/pub-sub/learning/websockets-browsers/)                                                                                          | [MQTT over WebSockets (Pub/Sub)](https://developers.cloudflare.com/pub-sub/learning/websockets-browsers/)                                     |
| **MQTT**               | Handle incoming messages to an MQTT broker with [Pub Sub](https://developers.cloudflare.com/pub-sub/learning/integrate-workers/)                                                                                                                                                                                                                  | Support for publishing MQTT messages to an MQTT topic is [coming soon](https://developers.cloudflare.com/pub-sub/learning/integrate-workers/) |
| **HTTP/3 (QUIC)**      | Accept inbound requests over [HTTP/3](https://www.cloudflare.com/learning/performance/what-is-http3/) by enabling it on your [zone](https://developers.cloudflare.com/fundamentals/setup/accounts-and-zones/#zones) in **Speed** > **Optimization** > **Protocol Optimization** area of the [Cloudflare dashboard](https://dash.cloudflare.com/). |                                                                                                                                               |
| **SMTP**               | Use [Email Workers](https://developers.cloudflare.com/email-routing/email-workers/) to process and forward email, without having to manage TCP connections to SMTP email servers                                                                                                                                                                  | [Email Workers](https://developers.cloudflare.com/email-routing/email-workers/)                                                               |
