Updated 2026-06-15
A TCP check connects to a host and port and confirms the connection succeeds — no HTTP involved. It's the right choice for databases, mail servers, game servers, or any custom protocol where you just need "is something listening and responding here."
Configuration options
- Port — the TCP port to connect to.
- Timeout — how long to wait for the connection (5 seconds by default).
- Send string (optional) — a string to send once connected.
- Expect string (optional) — a string to match in the reply, if you sent one. Leave both blank to check connectivity only.
When to use it
- A database port that shouldn't be reachable over HTTP.
- An SMTP, IMAP, or other non-HTTP service.
- Confirming a firewall or load balancer is passing traffic to a port before layering an HTTP check on top of it.
If the target does speak HTTP, an HTTP check gives you status-code and keyword matching that a plain TCP check can't.