Genderize.io API
Overview
Genderize.io predicts the likely gender of a given first name using a statistical model trained on a database of over 100 million names from around the world. It returns the predicted gender along with a probability score and the count of name samples used — giving you a confidence measure for each prediction. The API is free for up to 1,000 names per day without authentication.
Beginner Tip
This is one of the simplest APIs you can call — just pass a name in the URL query string and get back a JSON object. No API key required for the free tier. You can also pass a country_id parameter (ISO 3166-1 alpha-2) to get region-specific predictions, since the same name can lean differently by country.
Available Data
Example Response
{
"name": "michael",
"prediction": "male",
"count": 234567,
"probability": 0.87
} Field Reference
name The input first name as provided in the query, returned as-is. gender Predicted gender: "male", "female", or null if the name is not in the database. probability Confidence score from 0.0 to 1.0 — higher means stronger evidence for the predicted gender. count Number of data samples for this name in the Genderize.io database — larger counts mean more reliable predictions. Implementation Example
const url = "https://genderize.io/";
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
Matrix Score Breakdown
Fully tested on Apr 5, 2026
Technical Specifications
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