Klaxon

Klaxon started with a simple itch: we run about sixty services - sites, bots, scrapers, build machines - and wanted a phone to know the moment any of them breaks, without handing every alert to somebody else's cloud. So the whole thing is self-hosted: a small hub server runs on a machine you own, and anything that can make a web request - a script, a CI job, a Discord bot, a smart-home sensor, your browser - posts to one URL and becomes an alert on the companion iPhone app. Silence works too: services check in on a schedule, and when one goes quiet, the quiet itself raises the alarm. Around that core grew a whole toolbox: browser extensions that watch pages, prices and uptime (the first software we have ever shipped to the Chrome and Firefox stores), a VS Code extension that pings you when the long build you walked away from finishes, a Discord kit, RSS and MQTT bridges, desktop agents for the machines themselves, and Klaxon Desk, a macOS app for building alert rules visually. Alert history and attached logs never leave your own hardware.