# Genderize.io

> Genderize.io is a REST API that predicts the gender of a person from their first name, returning a probability score and the number of data rows examined. It is operated by Demografix ApS (Denmark) and is part of a suite of three name-based demographic APIs.

Genderize.io has been in operation for more than 12 years and bases its predictions on a dataset of over 908 million data rows covering 240+ countries and territories. It has been cited in over 1,400 academic papers (Google Scholar) and is used by organizations including The Guardian, MIT, Uber, Columbia University, Shopify, Nature, The Washington Post, and Yale University.

Important: Genderize.io predicts statistical gender likelihood — it does not determine biological sex or gender identity. Results are probabilistic, not deterministic.

## Documentation

- [Documentation Hub](https://genderize.io/documentation): Overview of all integration surfaces — API, MCP server, spreadsheet tool, and no-code workflows

## API

- [API Reference](https://genderize.io/documentation/api/reference): Full API reference with request/response formats, parameters, error codes, and examples
- [Example request](https://api.genderize.io?name=peter): `GET https://api.genderize.io?name=peter` returns `{"count":1346866,"name":"peter","gender":"male","probability":1.0}`
- [Country-scoped request](https://api.genderize.io?name=kim&country_id=dk): `GET https://api.genderize.io?name=kim&country_id=dk` returns `{"count":6494,"name":"kim","gender":"male","country_id":"DK","probability":0.97}` — while `?name=kim&country_id=us` returns female (0.94). Use `country_id` (ISO 3166-1 alpha-2) to scope predictions to a specific country.
- [Batch requests](https://genderize.io/documentation): Up to 10 names per request using `name[]=` parameter. Each name counts as one lookup against your quota.
- [Our Data](https://genderize.io/our-data): Open accuracy benchmarks — the live Genderize API scored against public datasets with a known gender for every person. 96.37% accuracy on 88,153 Olympic athletes (country-scoped), with every individual prediction published so the numbers can be checked.

## Pricing

- [Pricing](https://genderize.io/pricing): All tiers include access to all three APIs (genderize.io, agify.io, nationalize.io).
- Free: 2,500 names/month
- Basic: 25,000 names/month — $20/month
- Standard: 250,000 names/month — $60/month
- Plus: 2,500,000 names/month — $180/month
- Premium: 25,000,000 names/month — $540/month
- Yearly billing available (pay for 10 months, get 12)

## MCP Server

- [MCP Documentation](https://genderize.io/documentation/mcp): Connect any MCP-compatible AI client to Genderize.io
- Endpoint: `https://mcp.genderize.io`
- Tool: `predict_gender(name, country_id?)` — name can be a single string or a list of up to 100 names; country_id is an optional ISO 3166-1 alpha-2 code
- Authentication: `Authorization: Bearer YOUR_API_KEY` header — same API key as the REST API
- Quota: MCP requests count against your monthly plan quota
- [Claude Code setup](https://genderize.io/documentation/mcp/claude-code): One-line CLI install for Claude Code

## CLI

- [CLI — basic usage](https://genderize.io/documentation/cli): Command-line tool `demografix` — predict gender, age, and nationality from names in your terminal. Install, authentication, output formats, exit codes.
- [CLI — spreadsheets](https://genderize.io/documentation/cli/spreadsheets): Enrich a CSV/TSV/JSON/JSONL/XLSX file in place with prediction columns using `demografix enrich`. Dry-run costing and resume support.

## Tools

- [Spreadsheet tool](https://genderize.io/spreadsheets): Upload a spreadsheet and get gender, age, and nationality columns added — no code required
- [No-Code Integrations](https://genderize.io/documentation/no-code): Official integrations with n8n, Zapier, Make (formerly Integromat), and Pipedream
- [Community Libraries](https://genderize.io/libraries): Open-source libraries for Python, R, PHP, Ruby, Go, JavaScript, Java, C#, and more

## Resources

- [FAQ](https://genderize.io/faq): Common questions about data accuracy, billing, rate limits, and methodology
- [Case Studies](https://genderize.io/case-studies): Academic and journalistic use cases including The Guardian, Nature, and The Washington Post

## Related APIs

- [Agify.io](https://agify.io): Predict age from a name — same subscription, same API key
- [Nationalize.io](https://nationalize.io): Predict nationality from a name — same subscription, same API key