Whois MCP Server

@cyanheads/whois-mcp-server Look up domain registration, check registry record status, fetch DNS records, and resolve IPs and ASNs over RDAP and DNS-over-HTTPS via MCP. STDIO or Streamable HTTP. 6 Tools

---

Overview

Domain and network intelligence via RDAP and DNS-over-HTTPS. Look up domain registrations, check registry record status, fetch DNS records, and resolve IPs and ASNs to their registries. No API key required.

Tools

---

Capability reference

whois_lookup_domain tool

• Takes a fully qualified domain name and picks the registry's RDAP server through IANA bootstrap.
• Returns registrar, dates, nameservers, EPP status, DNSSEC, and registrant_redacted; DNSSEC and privacy stay null when the registry gives no evidence. Fails with rdap_no_coverage, domain_not_found, or rdap_invalid_domain_response (the response doesn't match the queried domain).
• include_registrar: true follows one registrar RDAP referral and adds registrar_detail (found, no_referral, or failed, plus source URL). Off by default; limited by RDAP_TIMEOUT_MS, and a failure keeps the registry result.

---

whois_check_availability tool

• Takes a fully qualified domain name.
• Returns registration_status: registered | not_found | unknown. available is false for a found registration and null otherwise, never true: a 404 means no record, not that the name can be registered.
• Known ICANN subdomains return non_registrable_domain with their registrable parent.

---

whois_get_dns tool

• Takes an ASCII DNS name (underscore labels like _dmarc.example.com are fine), up to 253 characters with 1–63-character labels. Optional types: A, AAAA, MX, TXT, NS, CNAME, SOA, CAA, PTR; defaults to A, AAAA, MX, TXT, NS.
• Returns records with TTLs and query_sources: [{type, source}], including empty answers and NXDOMAIN. Legacy source is cloudflare if any query got a successful Cloudflare response, otherwise nextdns.
• Resolver failure codes and truncated responses return errors after retries and fallback. CAA queries go to NextDNS.

---

whois_lookup_ip tool

• Takes an IPv4/IPv6 address with an optional CIDR prefix (0–32 / 0–128). Echoes the original ip.
• Returns org, country, abuse contact, provider CIDRs in cidrs (cidr only when there is exactly one), and a best-effort reverse DNS lookup: ptr_status: found | not_found | failed, with ptr_source_error on failure while the RDAP data is kept.
• include_routing: true adds routing (found | not_found | failed) with the RIS-observed prefix and origin_asns, from RIPEstat Network Info. Off by default; a routing failure keeps the RDAP and PTR results.
• Fails with invalid_ip, ip_not_found, ip_no_rdap_route (no RIR covers the address; not retryable), or private_range for 0.0.0.0/8, 10.0.0.0/8, 100.64.0.0/10, 127.0.0.0/8, 169.254.0.0/16, 172.16.0.0/12, 192.168.0.0/16, 255.0.0.0/8, ::1/128, fc00::/7, and fe80::/10.

---

whois_lookup_asn tool

• Takes an ASN from 1 to 4294967295, with an optional AS prefix (e.g., AS15169, AS 15169, +15169). Out-of-range numbers fail with invalid_asn.
• Returns name, org_name, country, rir, start_autnum, and end_autnum; fails with asn_not_found when no record exists.

---

whois_get_dossier tool

• Takes a fully qualified domain name and runs the registration and A/MX/NS/TXT lookups in parallel.
• Returns registration, DNS, domain age, privacy status, and inferred NS/MX providers. A failed lookup leaves the other's data in place and sets rdap_source_error or dns_source_error; both_legs_failed means neither succeeded.
• A null MX (0 .) means the domain accepts no mail.

---

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, optional RIPEstat Network Info) 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 is true when the registry shows it and null when there's no evidence
• Partial failure model — whois_get_dossier marks a failed lookup with a source_error field and continues; only both failing is an error
• Factual signals, not scores — age_days, privacy_redacted, ns_provider, mx_provider are real data, not synthesized risk scores

---

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://127.0.0.1:3010/mcp

Prerequisites

• Bun v1.4.0 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

1. Navigate into the directory:

cd whois-mcp-server

1. Install dependencies:

bun install

1. 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

---