Genderize API
Free API estimating the gender statistically associated with a first name, with a probability score. 100 requests/day, no key. Tested example and caveats.
Endpoint tested and returned HTTP 200 on 19 Aug 2026
What is the Genderize API?
Genderize is a free API that returns the gender statistically associated with a first name, along with a probability score and sample size. It allows 100 requests per day with no API key.
Genderize returns a predicted gender plus a `probability` between 0 and 1 and the `count` of records behind it. Those two fields are the important part: a 0.98 probability from 50,000 records is a very different claim from a 0.51 probability from 30.
This API should be used carefully. Gender is not reliably derivable from a name — many names are used across genders, vary by culture, and people's gender may not match any statistical association at all. Use it for aggregate dataset analysis, never to label an individual user or to personalise their experience.
Quick facts
- Base URL
https://api.genderize.io- Authentication
- No key for the free tier; optional key for higher volume.
- Rate limit
- 100 requests per day without a key.
- Pricing
- Free tier; paid plans available.
- CORS
- Enabled — callable directly from browser JavaScript
- Official docs
- Read the docs
How to use the Genderize API
Every request below was executed against the live API on 19 Aug 2026, and the response shown is the real body it returned — not an illustration.
1. Estimate the gender associated with a name
GET https://api.genderize.io?name=luc
curl 'https://api.genderize.io?name=luc'const res = await fetch("https://api.genderize.io?name=luc");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);import requests
res = requests.get("https://api.genderize.io?name=luc", timeout=20)
res.raise_for_status()
print(res.json()){
"count": 114766,
"name": "luc",
"gender": "male",
"probability": 0.99
}Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
name | string | Required | First name to analyse. luc |
country_id | string | Optional | ISO alpha-2 code to localise the estimate. FR |
Response fields
namestring- The name queried.
genderstring|null- `male`, `female`, or null when unknown.
probabilityfloat- Confidence from 0 to 1 — read this, not just `gender`.
countinteger- Number of records behind the estimate.
What you can build with the Genderize API
- Analyse aggregate gender distribution in an anonymised dataset
- Study name usage patterns across countries in research
- Teach probabilistic inference and its ethical limits
- Prototype with synthetic demographic data
Common errors and how to fix them
gender: null
Name not in the dataset.
Fix: Handle null; coverage is weakest for non-Western names.
Low probability value
The name is used across genders.
Fix: Set a probability threshold and treat anything below it as unknown rather than guessing.
429
Daily limit reached.
Fix: Cache per name; results are stable over time.
Genderize API — frequently asked questions
How accurate is Genderize?
It reports a statistical association, not a fact. Always read the `probability` and `count` fields — a low probability means the name is genuinely ambiguous, and the API is often wrong for individuals.
Is Genderize free?
Yes, 100 requests per day with no API key required. Paid plans raise the limit.
Should I use this to set a user's gender?
No. Gender cannot be reliably inferred from a name, and doing so misgenders people. Ask users directly if you need this information, and use the API only for aggregate analysis.
Does it support country-specific results?
Yes, pass `country_id` with an ISO alpha-2 code. The same name can skew differently by country, so this meaningfully improves aggregate accuracy.
Tools that pair with this API
JSON Formatter
Format, beautify and minify JSON online with 2-space, 4-space or tab indentation. Sort keys alphabetically and catch syntax errors instantly — free and private.
CSV to JSON Converter
Convert CSV to a JSON array of objects online. Header-row detection, comma/semicolon/tab delimiters and pretty-printed output — 100% in your browser.
Alternatives to Genderize API
If Genderize does not fit, these utility apis cover similar ground. Every one was called before publishing, and each links to its own reference page with a working curl command and the response it returned.
| API | What it does | Auth | CORS | Last verified |
|---|---|---|---|---|
| Agify | Free API that estimates age from a first name using public name data. No key for 100 requests/day. Tested curl example, live response and accuracy caveats. | No key | Yes | 19 Aug 2026 |
| Nationalize | Free API predicting likely nationality from a first name, returning ranked countries with probabilities. 100 requests/day, no key. Tested curl example. | No key | Yes | 19 Aug 2026 |
| Random User Generator | Free random user generator API with no key: names, addresses, emails, photos and logins in multiple nationalities. Seeded and reproducible. Tested example. | No key | Yes | 19 Aug 2026 |
| Bacon Ipsum | Free lorem ipsum style placeholder text API with no key. Generate meat-themed filler paragraphs or sentences via a simple GET request. Tested example. | No key | Yes | 19 Aug 2026 |
| Hebcal | Free Hebrew calendar API with no key: convert Gregorian to Hebrew dates and back, plus Jewish holidays, Shabbat times, Torah portions and yahrzeit calculations. Tested example included. | No key | Yes | 21 Aug 2026 |
| LectServe | Free lectionary API with no key: today's and Sunday's scripture readings from the Revised Common and ACNA lectionaries, with liturgical year and season. Tested example included. | No key | Yes | 21 Aug 2026 |
Genderize is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 19 Aug 2026; always check the official documentation before relying on this API in production, as terms and limits can change.