# Montastic > Montastic is a website uptime monitoring service. You add URLs > ("checkpoints") to monitor and get alerted by email, SMS, or webhook when > they go down or when a keyword appears/disappears on a page. This file > helps AI agents and tools discover and use the API. ## API - [OpenAPI specification (JSON)](https://montastic.com/openapi.json): Machine-readable REST API contract (OpenAPI 3.1). - [OpenAPI specification (YAML)](https://montastic.com/openapi.yaml): Same contract, in YAML. - [Developer reference](https://montastic.com/developers): Human-readable, interactive API docs. ## Authentication - [Your API key](https://montastic.com/me): Log in and copy your key, then send it as the `X-API-KEY` header on every request. ## Notes - A "checkpoint" is a single URL Montastic monitors. - Create one with `POST /checkpoints` and a JSON body `{"checkpoint":{"url":"https://example.com"}}`.