FernTool IP API & MCP server
Free, no-key API. CORS enabled (*). Please keep it under ~1 request/second.
Endpoints
- GET /ip
- Your IP, plain text
- GET /json
- Your IP + ISP, ASN, location, timezone
- GET /api/ip/{ip}
- Validate any IPv4/IPv6 + country, ASN, network (IP Geolocation by DB-IP, CC BY 4.0; IPtoASN)
- POST /api/batch
- Look up to 100 IPs:
{"ips":["8.8.8.8","1.1.1.1"]} - GET /api/whois/{q}
- RDAP WHOIS for a domain, IP or ASN
- GET /api/dns/{domain}?type=A,MX
- DNS records via Cloudflare DoH (A, AAAA, MX, TXT, NS, CNAME, SOA)
- GET /api/reverse-dns/{ip}
- PTR hostname + forward confirmation
- GET /api/subnet?cidr=…
- IPv4/IPv6 subnet calculator
- GET /openapi.json
- OpenAPI 3.1 spec
- POST /mcp
- MCP server (streamable HTTP)
Examples
curl https://www.ferntool.com
curl https://www.ferntool.com/json
curl https://www.ferntool.com/api/ip/8.8.8.8
curl https://www.ferntool.com/api/whois/example.com
curl "https://www.ferntool.com/api/dns/example.com?type=A,MX"
curl https://www.ferntool.com/api/reverse-dns/1.1.1.1
curl "https://www.ferntool.com/api/subnet?cidr=192.168.1.0/24"
curl -X POST https://www.ferntool.com/api/batch -H 'Content-Type: application/json' -d '{"ips":["8.8.8.8","185.220.101.1"]}'
curl -4 https://www.ferntool.com # force IPv4
curl -6 https://www.ferntool.com # force IPv6
MCP for AI agents
Add FernTool to any MCP client (Claude, Cursor, etc.) as a remote server: https://www.ferntool.com/mcp. Tools: get_my_ip, lookup_ip, batch_lookup_ip, validate_ip, whois_lookup, dns_lookup, reverse_dns, subnet_calc.
Lookups include flags (is_tor, is_datacenter, provider) and timezone. Please stay under ~40 network lookups per minute.
{"mcpServers":{"ferntool":{"url":"https://www.ferntool.com/mcp"}}}