Developer Reference

CallsignTools API

Free, no authentication required. All endpoints return JSON. CORS enabled for all origins.

Base URL: https://callsigntools.com · Rate limiting may be introduced in the future with fair-use API keys.

GET /api/callsign/{callsign}

Look up a single callsign by exact match. Returns full license details and history.

Example Request

GET https://callsigntools.com/api/callsign/W1AW

Example Response

{
  "unique_system_identifier": 1234567,
  "call_sign": "W1AW",
  "license_status": "A",
  "grant_date": "01/01/2020",
  "expired_date": "01/01/2030",
  "entity_name": "ARRL INC",
  "street_address": "225 MAIN ST",
  "city": "NEWINGTON",
  "state": "CT",
  "zip_code": "06111",
  "operator_class": "C",
  "frn": "0001234567",
  "history": [
    { "log_date": "01/01/2020", "code": "LIGRNT" },
    { "log_date": "12/15/2019", "code": "LIREN" }
  ]
}

GET /api/search?q={query}

Search licenses by callsign prefix, name, or city. Returns up to 50 results. History is not included in search results.

Parameter	Type	Description
q	string	Callsign prefix, name, or city. Case-insensitive.

Example Request

GET https://callsigntools.com/api/search?q=W1AW

Example Response

{
  "count": 2,
  "results": [
    {
      "call_sign": "W1AW",
      "license_status": "A",
      "entity_name": "ARRL INC",
      "city": "NEWINGTON",
      "state": "CT",
      "operator_class": "C",
      ...
    },
    ...
  ]
}

Field Reference

Field	Description
license_status	A = Active, E = Expired, C = Cancelled, T = Terminated
operator_class	N = Novice, T = Technician, G = General, A = Advanced, E = Extra, C = Club
grant_date / expired_date	Date format: MM/DD/YYYY
frn	FCC Registration Number
trustee_call_sign	For club/RACES licenses — the individual trustee's callsign
previous_call_sign	Prior callsign if the licensee has changed callsigns
history[].code	FCC action codes, e.g. LIGRNT (grant), LIREN (renewal), CANCEL (cancellation)

Error Responses

Status	Meaning
400	Missing or invalid parameter
404	Callsign not found
503	Database not yet available (initial ingest in progress)