whois-mcp-server

Tools

Six tools covering domain intelligence, DNS, and IP/ASN resolution:

whois_lookup_domain

Look up a domain's full RDAP registration record.

• RDAP-first via IANA auto-bootstrap — automatically selects the correct registry RDAP server per TLD

• Returns registrar, creation/expiry dates, nameservers, EPP status codes, DNSSEC delegation flag

• Surfaces registrant_redacted: true explicitly when privacy redaction is in effect (standard post-GDPR for gTLDs)

• Returns rdap_coverage: false for TLDs without RDAP coverage rather than silently failing

• Includes last_update_of_rdap_db event timestamp for data freshness transparency

whois_check_availability

Check whether a domain name is registered or available to register.

• RDAP 404 = available (available: true) — exploits the RDAP spec's intended behavior

• Returns available: false with registrar and expiry_date when registered

• Returns available: null with rdap_coverage: false for TLDs without RDAP — cannot determine availability

• Optimized for bulk name sweeps — thin response, no unnecessary fields

whois_get_dns

Fetch DNS records via DNS-over-HTTPS.

• Cloudflare 1.1.1.1 primary, Google 8.8.8.8 fallback (used for CAA records where Cloudflare returns raw hex)

• Supports A, AAAA, MX, TXT, NS, CNAME, SOA, CAA, PTR — multiple types in one call

• Returns records with TTLs and the resolving source (cloudflare or google)

• nxdomain: true in result (not an error) when the domain doesn't exist in DNS

whois_lookup_ip

Look up an IP address or CIDR block via RIR RDAP.

• Auto-routes to the correct RIR (ARIN, RIPE, APNIC, LACNIC, AFRINIC) via IANA IP bootstrap

• Returns netblock CIDR, org name, country, abuse contact email

• Fetches PTR (reverse DNS) via DoH as a best-effort step — ptr: null on failure, not an error

• Validates and rejects private/reserved ranges (RFC 1918, loopback, link-local) with a clear error

whois_lookup_asn

Resolve an ASN to its org name, country, and RIR.

• Accepts AS15169 or bare integer 15169 format

• Routes to the correct RIR RDAP endpoint via IANA ASN bootstrap

• Returns name, org, country, rir, start_autnum, end_autnum

whois_get_dossier

One-call domain triage aggregating registration and DNS data in parallel.

• Runs RDAP domain lookup and DoH (A, MX, NS, TXT) in parallel via Promise.allSettled

• Inferred signals: age_days, privacy_redacted, registrar, ns_provider (from NS records), mx_provider (from MX records)

• No synthesized risk scores — factual signals only; the agent decides the verdict

• Partial results surfaced when one leg fails (source_error on the failed leg)

• Both-legs-fail throws ServiceUnavailable; individual leg failures are data, not errors

Related MCP server: domain-checker

Features

Built on @cyanheads/mcp-ts-core:

• Declarative tool definitions — single file per tool, framework handles registration and validation

• Unified error handling — handlers throw, framework catches, classifies, and formats

• Pluggable auth: none, jwt, oauth

• Swappable storage backends: in-memory, filesystem, Supabase, Cloudflare KV/R2/D1

• Structured logging with optional OpenTelemetry tracing

• STDIO and Streamable HTTP transports

Domain and network intelligence:

• RDAP over HTTPS — no port-43 TCP dependency, runs on Node, Bun, and Cloudflare Workers

• IANA bootstrap auto-selection — correct registry RDAP server picked per TLD, RIR, or ASN range; bootstrap JSON cached (TTL 24h) in tenant state

• DNS-over-HTTPS via Cloudflare and Google — resilient dual-provider with per-type routing (Google for CAA; Cloudflare for all others)

• No API keys required — all sources (IANA, registry RDAP endpoints, RIR RDAP, Cloudflare DoH, Google DoH) are public and keyless

Agent-friendly output:

• Explicit coverage signals — rdap_coverage: false tells the agent the TLD lacks RDAP rather than returning a confusing error

• Privacy redaction surfaced as a field — registrant_redacted: true rather than silently absent contact data

• Partial failure model — whois_get_dossier marks individual legs with source_error and continues; only both-legs-fail escalates to an error

• Factual signals, not scores — age_days, privacy_redacted, ns_provider, mx_provider are real data; agents chain into threat-intel or risk servers for enrichment

Getting started

No API keys or accounts required. Add the following to your MCP client configuration file.

{
  "mcpServers": {
    "whois-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/whois-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "whois-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/whois-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "whois-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": [
        "run", "-i", "--rm",
        "-e", "MCP_TRANSPORT_TYPE=stdio",
        "ghcr.io/cyanheads/whois-mcp-server:latest"
      ]
    }
  }
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.3.0 or higher (or Node.js v24+).

• No API keys required — all data sources are public.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/whois-mcp-server.git

2. Navigate into the directory:

cd whois-mcp-server

3. Install dependencies:

bun install

4. Configure environment:

cp .env.example .env
# All vars are optional — defaults work for most use cases

Configuration

See .env.example for the full list of optional overrides.

Running the server

Local development

• Build and run:

  bun run rebuild
  bun run start:stdio
  # or
  bun run start:http

• Run checks and tests:

  bun run devcheck   # Lint, format, typecheck, security
  bun run test       # Vitest test suite
  bun run lint:mcp   # Validate MCP definitions against spec

Docker

docker build -t whois-mcp-server .
docker run --rm -p 3010:3010 whois-mcp-server

The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/whois-mcp-server. OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Development guide

See CLAUDE.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic

• Use ctx.log for request-scoped logging, ctx.state for tenant-scoped storage (IANA bootstrap cache)

• Register new tools via src/index.ts tools array

• Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Contributing

Issues and pull requests are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

Apache-2.0 — see LICENSE for details.