Rybbit

Rybbit is an open source connection monitoring tool that keeps an eye on your network links by checking TCP socket availability. It runs lightweight health probes against defined endpoints and surfaces failures quickly through its integrated alerting. The tool is designed for ops teams who need simple, reliable visibility into whether their services are reachable.

It supports TCP health checks with configurable intervals and timeouts, and can alert via Slack or custom webhooks when a connection drops. The agent runs on Linux and is built with Go, making it easy to deploy as a single binary or container. Configuration uses YAML files so you can version control your monitoring setup alongside your infrastructure.

Rybbit is a good fit for small teams or individual sysadmins who want socket-level monitoring without the overhead of a full observability stack. It is open source under the MIT license and free to use. The project is maintained by Rybbit IO and has an active GitHub repository where you can file issues or contribute.