domains-mcp

An MCP server that lets Claude (and other agents) check domain availability, look up registration details, and suggest available names across TLDs.

Availability comes entirely from free, open protocols — RDAP with a port-43 WHOIS fallback. No API keys, no accounts, no paid services.

Tools

| Tool | What it does | | --- | --- | | check_domain | Is a single domain available? Accepts bare names, URLs, and IDNs. | | check_domains | Bulk-check a list of domains (max 50, runs concurrently). | | suggest_domains | Given a base name, return the available options across a set of TLDs. | | domain_info | Registrar, status, creation/expiry dates, and nameservers for a domain. |

Each result is one of available, registered, or unknown. unknown means no source could answer definitively — the server never guesses an answer.

Install

The package is published on npm: domains-mcp.

Run it directly with npx (no install needed):

npx domains-mcp

…or install it globally:

npm install -g domains-mcp

Use with Claude

Add to your MCP client configuration (e.g. Claude Desktop's claude_desktop_config.json):

{
  "mcpServers": {
    "domains": {
      "command": "npx",
      "args": ["-y", "domains-mcp"]
    }
  }
}

Then ask things like: "Is acme-robotics.com available?", "Check these five domains for me," or "Suggest available domains for the name 'lumina'."

Local development

git clone https://github.com/fulldev-pl1/domains-mcp.git
cd domains-mcp
npm install
npm run build

Quick smoke test (no MCP client needed):

npm run check -- google.com some-free-name-12345.com github.io münchen.de

Configuration (all optional)

| Variable | Purpose | Default | | --- | --- | --- | | REQUEST_TIMEOUT_MS | Per-request network timeout | 5000 | | CACHE_TTL_SECONDS | TTL for the in-memory availability cache | 300 | | CONCURRENCY | Max concurrent lookups during bulk operations | 8 | | DEFAULT_TLDS | Comma-separated TLDs used by suggest_domains | com,net,org,io,ai,co,dev,app,xyz,me |

How it works

1. The input domain is normalized (URL stripping, www. removal, IDN → Punycode, validation).
2. RDAP: the TLD is resolved to its RDAP server via the IANA bootstrap registry. A 404 means available; a 200 returns full registration data.
3. WHOIS fallback: if the TLD has no RDAP service (or RDAP is inconclusive), the server asks IANA for the TLD's WHOIS server, queries it, and pattern-matches the response.
4. Results are cached briefly to cut latency and respect registry rate limits.

See DESIGN.md for the full architecture and the rationale behind these decisions.

Known limitations

Some ccTLD WHOIS servers (e.g. DENIC for .de) return restricted or unusually formatted responses; those may come back as unknown rather than a guess. RDAP/WHOIS report registration status, not whether a taken domain is for sale.

License

MIT