M
API Matrix

Callook.info API

⭐ Beginner's Pick Open Data / No Auth Required Beginner HTTPS
Free to Use Varies (check documentation)
82 Score
Grade A
Visit Official Site Compare Alternatives

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

phone number validation
carrier information
country code
line type

Example Response

JSON Response 
{
  "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 

const url = "https://callook.info/";
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

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.

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 15/20
🔒 Security 15/15
🛠 Developer XP 15/20
✓ Reliability 7/15
Response Time 204ms

Fully tested on Apr 5, 2026

Technical Specifications

Auth No Auth
HTTPS REQUIRED
CORS UNKNOWN
Category Open Data
Difficulty Beginner
Verified: 2026-04-04

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