API Reference

Every endpoint below is free, requires no API key and returns camelCase JSON. Base URL: https://onlinechecker.io

Payments & fraud

GET /api/v1/bin/lookup/

Look up card issuer, brand, type and country by the first 6–8 digits of a card number.

curl -s "https://onlinechecker.io/api/v1/bin/lookup/?bin=457199"
GET /api/v1/bin/

List and filter BIN records directly.

curl -s "https://onlinechecker.io/api/v1/bin/?bin=457199"
GET /api/v1/card/check/

Validate a card number with the Luhn algorithm and brand-specific length rules.

curl -s "https://onlinechecker.io/api/v1/card/check/?card=4242424242424242"
POST /api/v1/checker/

Score an order's fraud risk using email, IP address, card BIN, cardholder name and phone.

curl -X POST https://onlinechecker.io/api/v1/checker/ \
  -H "Content-Type: application/json" \
  -d '{"email":"[email protected]","ipAddress":"203.0.113.10","card":"457199","name":"Jane Doe","phone":"+447911123456"}'
GET /api/v1/iban/check/

Validate an IBAN's structure and mod-97 checksum, and identify its issuing country.

curl -s "https://onlinechecker.io/api/v1/iban/check/?iban=DE89370400440532013000"

Network & IP

GET /api/v1/checker/ip/lookup/

Geolocate an IP address and check whether it belongs to a datacenter or VPN/proxy network.

curl -s "https://onlinechecker.io/api/v1/checker/ip/lookup/?ip=203.0.113.10"
GET /api/v1/vpn/check/

Check whether an IP address belongs to a known VPN or proxy network.

curl -s "https://onlinechecker.io/api/v1/vpn/check/?ip=203.0.113.10"
GET /api/v1/datacenter/check/

Check whether an IP address belongs to a known datacenter/hosting network.

curl -s "https://onlinechecker.io/api/v1/datacenter/check/?ip=203.0.113.10"
GET /api/v1/tor/check/

Check whether an IP address is a known Tor exit node.

curl -s "https://onlinechecker.io/api/v1/tor/check/?ip=203.0.113.10"
GET /api/v1/subnet/calculate/

Network address, broadcast, netmask and usable host range for any IPv4/IPv6 CIDR.

curl -s "https://onlinechecker.io/api/v1/subnet/calculate/?cidr=192.168.1.0%2F24"
GET /api/v1/asn/lookup/

Look up who owns an IP address: autonomous system number and organization.

curl -s "https://onlinechecker.io/api/v1/asn/lookup/?ip=8.8.8.8"

Domain, DNS & SSL

GET /api/v1/whois/lookup/

Look up domain registration details: registrar, owner, and important dates.

curl -s "https://onlinechecker.io/api/v1/whois/lookup/?domain=example.com"
GET /api/v1/rdap/lookup/

Structured domain registration data via RDAP: contacts, events, status and DNSSEC.

curl -s "https://onlinechecker.io/api/v1/rdap/lookup/?domain=example.com"
GET /api/v1/dns/lookup/

Full DNS lookup for a hostname across A, AAAA, MX, TXT and other record types.

curl -s "https://onlinechecker.io/api/v1/dns/lookup/?hostname=example.com"
GET /api/v1/ssl/lookup/

Inspect a certificate's issuer, validity, SAN domains and trust chain for any host.

curl -s "https://onlinechecker.io/api/v1/ssl/lookup/?hostname=example.com"
GET /api/v1/domain-age/check/

Check a domain's registration date and age — a freshly registered domain is a well-known fraud signal.

curl -s "https://onlinechecker.io/api/v1/domain-age/check/?domain=example.com"

Identity & device

GET /api/v1/email/check/

Syntax, MX records, disposable domains, role-based addresses and optional SMTP verification.

curl -s "https://onlinechecker.io/api/v1/email/check/[email protected]&skip_smtp=true"
GET /api/v1/phone/check/

Phone country, VoIP/prepaid line type and comparison with an IP geolocation country.

curl -s "https://onlinechecker.io/api/v1/phone/check/?phone=%2B447911123456&ip=203.0.113.10"
GET /api/v1/mac/lookup/

Identify the manufacturer behind a MAC address from the IEEE OUI registry.

curl -s "https://onlinechecker.io/api/v1/mac/lookup/?mac=3C%3A22%3AFB%3A00%3A00%3A00"
GET /api/v1/ua/parse/

Browser, OS and device type from a User-Agent string, with bot/crawler detection.

curl -s "https://onlinechecker.io/api/v1/ua/parse/?ua=Mozilla%2F5.0..."

Utilities

POST /api/v1/notes/create/

Save a name and text. Response is JSON with the note's shareable link.

curl -X POST https://onlinechecker.io/api/v1/notes/create/ \
  -H "Content-Type: application/json" \
  -d '{"name":"Grocery list","text":"Milk, eggs, bread"}'
GET /notes/<id>/

Fetch a note by its id. Response is the raw text itself (text/plain), not JSON.

curl -s https://onlinechecker.io/notes/aB3dE9j/
GET /api/v1/whoami/

What your own connection reveals: IP, geolocation, VPN/Tor/datacenter flags and browser details.

curl -s "https://onlinechecker.io/api/v1/whoami/"