Overview

Callook.info is a free API that lets you look up United States amateur (ham) radio callsigns. No API key is required, making it very easy to get started. It returns structured data about the licensee including their name, location, and license class.

Beginner Tip

Simply append a callsign to the base URL (e.g., /W1AW) to retrieve license details. Add /data.json to the path to get a clean JSON response.

Available Data

The kind of data this API exposes, based on its documentation. We could not call the endpoint to confirm the exact field names.

phone number validation
carrier information
country code
line type

Example Response

Illustrative shape only — we were not able to call this endpoint (it requires credentials or exposes no public sample URL), so the fields below show the kind of data this API returns rather than a recorded response.

JSON Response · Illustrative
{
  "status": "success",
  "data": {
    "result": "Data from Callook.info",
    "description": "United States ham radio callsigns",
    "timestamp": "2025-01-15T10:00:00Z"
  }
}

Field Reference

status License status, typically VALID or INVALID.
type Type of license, such as PERSON or CLUB.
name Object containing first and last name of the licensee.
address Mailing address associated with the license.
location Latitude and longitude of the licensee location.
otherInfo Additional details including license class, grant date, and expiry date.

Implementation Example

Calls a real endpoint of this API. Replace any placeholder credentials with your own key.

Request
const url = "https://callook.info/W1AW/data.json";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

Generated guidance based on this API's documentation, not observed by us. Treat it as a starting point and check against the provider's own error reference.

404 or empty response The callsign is not found in the FCC database or is incorrectly formatted.
Ensure the callsign is uppercase with no spaces, and verify it is a valid US amateur radio license.
HTML returned instead of JSON Requesting the base callsign URL returns an HTML page by default.
Append /data.json to the URL to force a JSON response, for example /W1AW/data.json.
Rate limit exceeded Sending too many requests in a short time may result in temporary blocking.
Add a small delay (e.g., 500ms) between requests when doing batch lookups.

Metadata Score Breakdown

Estimated from metadata — endpoint not independently tested

This score is estimated from observable metadata — HTTPS support, authentication model, declared CORS, and documentation reachability — because the API requires authentication or exposes no publicly testable endpoint. The five-signal breakdown is only shown for live-tested APIs.

Metadata estimate · endpoint not independently tested

Technical Specifications

Auth No Auth
HTTPS REQUIRED
CORS UNKNOWN
Category Open Data
Difficulty Beginner
Listing details not endpoint-verified

Related Tags

Similar APIs

View All →