# Domain Sentinel

> Domain monitoring service: availability lookups over RDAP with WHOIS and DNS fallbacks, watchlists with daily checks, change history, DNS and SSL certificate monitoring, email alerts. Free tier, REST API and a remote MCP server for AI assistants.

## Product

- [Domain lookup](https://www.domain-sentinel.com/en/lookup): check availability and registration data for any domain
- [Registry change history](https://www.domain-sentinel.com/en/lookup): timeline of transfers, renewals and nameserver changes per domain
- [Supported TLDs](https://www.domain-sentinel.com/en/tlds): how each TLD is checked and which RDAP server answers
- [RDAP and WHOIS servers by TLD](https://www.domain-sentinel.com/en/rdap-servers): every RDAP base URL and WHOIS port 43 server, grouped by registry with the TLDs it serves

## For developers and AI assistants

- [MCP server](https://www.domain-sentinel.com/en/mcp): connect Claude, Cursor or any MCP client to https://api.domain-sentinel.com/mcp
- [REST API documentation](https://www.domain-sentinel.com/en/docs): GET /v1/lookup/{domain}, anonymous or with an API key
- [OpenAPI document](https://api.domain-sentinel.com/v1/openapi.json)

## Use cases

- [Domain availability alerts](https://www.domain-sentinel.com/en/domain-availability-alerts)
- [Domain expiry reminders](https://www.domain-sentinel.com/en/domain-expiry-reminders)
- [Brand protection](https://www.domain-sentinel.com/en/brand-protection)
- [DNS monitoring](https://www.domain-sentinel.com/en/dns-monitoring)
- [Domain extension monitoring](https://www.domain-sentinel.com/en/domain-extension-monitoring)
- [WHOIS API](https://www.domain-sentinel.com/en/whois-api)
- [DNS lookup tool](https://www.domain-sentinel.com/en/dns-lookup)

## Blog

- [Blog index](https://www.domain-sentinel.com/en/blog): guides on WHOIS, RDAP, DNS, domain lifecycle and brand protection