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Query real-time WHOIS records for any AS number. Returns organizational details, CIDR block inventory, BGP peer relationships, and structured RIR contact data - sourced live from all 5 RIRs.
The ASN Lookup API provides a complete network operator profile for any Autonomous System Number - including WHOIS registration, advertised CIDR prefixes, BGP relationships (upstreams, downstreams, peers), structured RIR contact records, and raw WHOIS text. Perfect for network analysis, threat intelligence, and infrastructure profiling.
Authorize every request with your API key, passed either as a header or as a query parameter:
X-apiKeyapiKeyThis is version v1.0 of the API.
The following parameters can be used in your API requests. All parameters are passed as query string parameters.
formatoptionalStringdefault: jsonResponse format: 'json' (default) or 'xml'.
asnrequiredStringAutonomous System Number with or without 'as'
A successful request returns a 200 OK response with a JSON object containing the ASN data. The response includes the top-level fields listed below. See the response preview on the right for the full JSON structure.
asNumberAS number to query live WHOIS, e.g., 1234, etc.
asNameAS name for the autonomous system
orgNameOrganization name holding the AS number
descriptionDescription of the autonomous system
orgHandleOrganization handle or unique identifier
countryCountry code where the AS is registered
domainDomain associated with the AS
websiteWebsite URL of the organization
allocationStatusAllocation status of the AS number (e.g., allocated, assigned)
numOfIPv4RoutesNumber of IPv4 routes announced by this AS
numOfIPv6RoutesNumber of IPv6 routes announced by this AS
whoisHostWHOIS host server used to query the AS number
dateAllocatedDate when the AS was allocated in yyyy-MM-dd format (can be empty string)
typeType of the organization (e.g., BUSINESS, ISP)
whoisResponseRaw WHOIS response from the WHOIS server
legacyRoutesList of legacy routes if any
route (String), origin (String), originName (String), isp (String), numberOfIps (Integer)
asNumber (String), description (String), country (String)
asNumber (String), description (String), country (String)
asNumber (String), description (String), country (String)
emailContacts (Array<String>), abuseContacts (Array<String>)
status (Boolean), whois_server (String), aut_nums (Array<Object>), organization (Object), technical_contacts (Array<Object>), …
handle (String), name (String), address (Array<String>), street (String), city (String), …
handle (String), name (String), email (Array<String>), phone (Array<String>), source (String)
handle (String), name (String), email (Array<String>), phone (Array<String>), source (String)
aut_num (String), as_handle (String), as_name (String), tech_contacts (Array<String>), abuse_contacts (Array<String>), …
handle (String), name (String), email (Array<String>), phone (Array<String>), source (String)
handle (String), name (String), email (Array<String>), phone (Array<String>), source (String)
handle (String), name (String), email (Array<String>), phone (Array<String>), source (String)
Besides the response body, every response carries custom headers you can use to track credit usage, and concurrency usage on endpoints that enforce a concurrency limit. See the Custom Response Headers documentation and the endpoints with concurrency limits for more details.
X-Concurrent-Threadsheaderconcurrency-limited endpointsSpecifies the maximum number of concurrent requests allowed.
X-Concurrent-Threads-Activeheaderconcurrency-limited endpointsIndicates the number of active concurrent requests being processed.
X-AF-Credits-Costheaderall responsesSpecifies the number of credits consumed by the current request.
See the HTTP Status Codes documentation for a complete reference of common API errors and HTTP status codes.
Request-param asn (******) is not valid.
Request-param 'format' (<format>) is not valid. Supported formats are json, xml