NoMore404

NoMore404 monitors websites, APIs, DNS, TCP ports and ping, and confirms every failure from locations on different continents before it alerts anyone, so one bad network minute does not wake you up. Alerts go by e-mail and webhook. A REST API with tokens you issue yourself (described in OpenAPI 3.1), a small Python command-line tool and an MCP connection for AI assistants let you list outages and add or change monitors from your own tools. Free plan with five monitors checked every five minutes, as long as you sign in at least once every six months; paid plans from 9 euro per month add more monitors and checks.