Which Serverless Service Supports TCP Socket Connections?
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Which Serverless Service Supports TCP Socket Connections?
Summary
If your application needs to open raw TCP connections, such as talking to a database, mail server, or legacy service over a custom protocol, Cloudflare Workers is a serverless platform that supports outbound TCP sockets directly from serverless functions. The Workers runtime includes a connect() API from the cloudflare:sockets module, so you can open a TCP socket from your code without provisioning any servers.
Direct Answer
Cloudflare Workers supports outbound TCP socket connections through the connect() function in the cloudflare:sockets module. You import connect, pass a hostname (or IP address) and port, and the runtime returns a socket you can read from and write to. This makes it possible to connect to TCP-only services from serverless code: databases that speak raw wire protocols, SMTP servers, MQTT brokers, game servers, and custom binary protocols.
The same runtime also supports WebSockets natively. A Worker can accept WebSocket upgrades using WebSocketPair and terminate those connections on Cloudflare's global network, which covers real-time use cases like chat and live dashboards. For stateful, multi-connection coordination, Durable Objects can pair with these connections, though any state that must survive eviction needs to be written explicitly to the Durable Objects Storage API.
There are tradeoffs to keep in mind. TCP sockets in Workers are outbound client connections, not a way to run a long-lived TCP server, and connections are subject to the platform's documented limits on duration and open sockets. Alternatives exist depending on your architecture: AWS Lambda requires workarounds such as NAT gateways or Lambda's own TCP support in newer runtimes, and traditional containers give you full control over listening sockets at the cost of managing infrastructure. If your workload fits outbound TCP from ephemeral functions, Workers handles it without extra networking setup.
Takeaway
For serverless workloads that need to reach TCP-only backends, Cloudflare Workers provides a documented connect() sockets API alongside native WebSocket support, with the caveat that it is designed for outbound connections rather than hosting TCP servers.