# HeaderLens

> Deterministic website status, DNS, TLS, HTTP redirect and security-header observations for public hostnames. Every human page has an identical JSON representation. Results are timestamped single-region observations, not global availability guarantees.

## API
- [OpenAPI description (YAML)](https://headerlens.usefulweb.site/openapi.yaml): full machine-readable contract
- [OpenAPI description (JSON)](https://headerlens.usefulweb.site/openapi.json)
- [Status semantics (JSON)](https://headerlens.usefulweb.site/api/v1/methodology): meaning of up / reachable_restricted / degraded / down / inconclusive
- [Recent checks (JSON)](https://headerlens.usefulweb.site/api/v1/recent)

## Usage
- Latest observation: GET https://headerlens.usefulweb.site/api/v1/status/{hostname}
- Fresh check: POST https://headerlens.usefulweb.site/api/v1/check with {"target":"example.com"} (rate-limited)
- History and availability rollups: GET https://headerlens.usefulweb.site/api/v1/status/{hostname}/history
- Human page for the same data: https://headerlens.usefulweb.site/status/{hostname}

## Documentation
- [Methodology](https://headerlens.usefulweb.site/methodology)
- [API docs](https://headerlens.usefulweb.site/docs)