io.github.cyanheads/whois-mcp-server

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Overview

Domain and network intelligence via RDAP and DNS-over-HTTPS. Look up domain registrations, check availability, fetch DNS records, and resolve IPs and ASNs to their registries — all via public, keyless data sources. Runs as a stdio process or a local Streamable HTTP server.

Tools

Tool	Description
whois_lookup_domain	Full domain registration record — registrar, created/expiry dates, nameservers, EPP status, DNSSEC, registrant org
whois_check_availability	Check whether a domain is registered or available for registration
whois_get_dns	DNS records for any hostname via DNS-over-HTTPS (A, AAAA, MX, TXT, NS, CNAME, SOA, CAA, PTR)
whois_lookup_ip	IP or CIDR netblock, org, country, abuse contact, and reverse DNS via RIR RDAP
whois_lookup_asn	Resolve an ASN to its org name, country, and RIR source
whois_get_dossier	One-call domain triage — registration + DNS in parallel, normalized into a single record with factual signals

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Capability reference

whois_lookup_domain _tool

• RDAP-first via IANA auto-bootstrap — automatically selects the correct registry RDAP server per TLD
• Returns registrar, creation/expiry dates, nameservers, EPP status codes, and DNSSEC delegation flag
• Surfaces registrant_redacted: true when privacy redaction is in effect (standard post-GDPR for gTLDs)
• Throws rdap_no_coverage when the TLD has no RDAP server in the IANA bootstrap — use whois_check_availability instead
• Throws domain_not_found on an RDAP 404 (domain not registered) — use whois_check_availability to confirm

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whois_check_availability _tool

• RDAP 404 response maps to available: true
• Registered domains return available: false with registrar and expiry_date
• available: null with rdap_coverage: false when the TLD has no RDAP coverage — availability cannot be determined
• Thin response optimized for bulk name sweeps — no extra fields

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whois_get_dns _tool

• Supports A, AAAA, MX, TXT, NS, CNAME, SOA, CAA, PTR; multiple types fetched in parallel; defaults to A, AAAA, MX, TXT, NS when types is omitted
• Cloudflare primary, NextDNS fallback per type (CAA always uses NextDNS — Cloudflare returns raw hex wire format for it)
• Returns records with TTLs and the resolving source (cloudflare or nextdns)
• nxdomain: true in the result (not an error) when the domain doesn't exist in DNS

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whois_lookup_ip _tool

• Accepts an IPv4/IPv6 address or CIDR block; 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
• Throws private_range for RFC 1918, loopback, and link-local addresses — no RIR RDAP record exists for them
• Throws ip_not_found on an RIR RDAP 404

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whois_lookup_asn _tool

• Accepts AS15169 or bare integer 15169 format
• Routes to the correct RIR RDAP endpoint via IANA ASN bootstrap
• Returns name, org_name, country, rir, start_autnum, end_autnum
• Throws asn_not_found on an RIR RDAP 404

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whois_get_dossier _tool

• 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 (rdap_source_error / dns_source_error on the failed leg)
• Throws both_legs_failed only when both RDAP and DNS fail; individual leg failures are data, not errors

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Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

RDAP / DNS-specific:

• RDAP over HTTPS — no port-43 TCP dependency
• IANA bootstrap auto-selection — correct registry RDAP server picked per TLD, RIR, or ASN range; bootstrap JSON cached in-memory for 24h
• DNS-over-HTTPS via Cloudflare and NextDNS — dual-provider with per-type routing (NextDNS for CAA; Cloudflare for all others) and automatic fallback
• No API keys required — all sources (IANA, registry RDAP endpoints, RIR RDAP, Cloudflare DoH, NextDNS DoH) are public and keyless

Agent-friendly output:

• Coverage signaled two ways — rdap_coverage: false returned as data by whois_check_availability and whois_get_dossier, while whois_lookup_domain throws rdap_no_coverage for the same case
• 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 a source_error field 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, not synthesized risk scores

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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

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Configuration

Variable	Description	Default
RDAP_TIMEOUT_MS	HTTP timeout for RDAP requests in milliseconds.	5000
DOH_TIMEOUT_MS	HTTP timeout for DNS-over-HTTPS requests in milliseconds.	3000
RDAP_MAX_RETRIES	Max retry attempts on transient RDAP failures.	2
DOH_MAX_RETRIES	Max retry attempts on transient DoH failures.	2
MCP_TRANSPORT_TYPE	Transport: stdio or http.	stdio
MCP_HTTP_PORT	Port for HTTP server.	3010
MCP_AUTH_MODE	Auth mode: none, jwt, or oauth.	none
MCP_LOG_LEVEL	Log level (RFC 5424).	info
OTEL_ENABLED	Enable OpenTelemetry instrumentation.	false

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

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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.

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Project structure

Path	Purpose
src/index.ts	Entry point — starts the app.
src/app.ts	createApp() options — registers tools, inits services, declares the session mode.
src/config/	Server-specific environment variable parsing and validation (Zod).
src/services/rdap/	RDAP client — IANA bootstrap cache, domain/IP/ASN lookup, retry.
src/services/doh/	DNS-over-HTTPS client — Cloudflare primary, NextDNS fallback.
src/mcp-server/tools/	Tool definitions (*.tool.ts).
tests/	Vitest tests mirroring src/.
docs/	Design and API reference documents.

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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
• Register new tools via src/app.ts's tools array
• Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

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Contributing

Issues are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

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License

Apache-2.0 — see LICENSE for details.