WatchYourLAN is a self-hosted network discovery and monitoring tool written in Go. It scans local network interfaces using ARP requests to detect connected devices, tracks their online and offline status over time, and identifies when new or previously unseen hosts appear on the network. The application stores host data and connection history in either SQLite or PostgreSQL, and can export metrics to InfluxDB or expose a Prometheus endpoint for long-term storage and visualization in dashboards like Grafana.
The tool provides a REST API for programmatic management of monitored hosts, including adding, editing, deleting, and querying individual or all hosts, as well as triggering network rescans and checking port connectivity. Notifications are sent via the Shoutrrr bridge when new devices are detected, supporting multiple messaging platforms. Wake-on-LAN functionality allows sending magic packets to remotely power on sleeping devices on the local network.
Configuration is handled through a web interface or environment variables, and users can supply custom MAC vendor name mappings to override the built-in list. The application can run fully offline by loading all static assets locally.