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The Public APIs directory contains hundreds of free APIs organized by category. This guide will help you efficiently search and filter APIs to find exactly what you need for your project.

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Browsing by category

APIs are organized into 40+ categories to help you quickly narrow down your search:
  • Animals - Pet adoption, animal facts, and wildlife data
  • Anime - Anime discovery, tracking, quotes, and images
  • Art & Design - Museum collections, icons, and design resources
  • Authentication & Authorization - User management and auth platforms
  • Blockchain - Cryptocurrency and blockchain data
  • Books - Religious texts, poetry, and literature APIs
  • Business - Analytics, CRM, and business tools
  • Cryptocurrency - Trading platforms and crypto prices
  • Currency Exchange - Exchange rates and conversion
  • Development - Tools for developers including testing and monitoring
  • Finance - Stock market and financial data
  • Games & Comics - Gaming APIs and comic resources
  • Government - Open government data
  • Health - Medical and health information
  • Weather - Weather forecasts and climate data
And many more! Check the Index to see all available categories.

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Understanding the table columns

Each API entry in the directory provides key information across five columns:

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API

The name of the API with a link to its official documentation. API names are listed alphabetically within each category and do not include the TLD (e.g., “Gmail” not “Gmail.com”).

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Description

A brief summary (100 characters or less) of what the API does and what data or services it provides. Examples:
  • “NASA data, including imagery”
  • “Random pictures of dogs”
  • “IP/domain/URL reputation”

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Auth

Indicates the type of authentication required to use the API:
  • OAuth - The API uses OAuth authentication
  • apiKey - Requires a private API key or token
  • X-Mashape-Key - Uses a specific Mashape header key
  • User-Agent - Requires a User-Agent header
  • No - No authentication needed (completely open)
See the Authentication guide for detailed explanations of each type.

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HTTPS

Shows whether the API supports HTTPS protocol:
  • Yes - API supports secure HTTPS connections
  • No - API only available over HTTP

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CORS

Indicates Cross-Origin Resource Sharing support:
  • Yes - API supports CORS (can be used in browser-based apps)
  • No - API does not support CORS (server-side only)
  • Unknown - CORS support status is not verified
Learn more about CORS in the CORS compatibility guide.

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Tips for finding the right API

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Start with the category

If you know what type of data or service you need, browse the relevant category first. For example:
  • Building a weather app? Check Weather
  • Need geolocation? Look at Geocoding
  • Want to add memes or fun content? Try Entertainment

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Consider authentication requirements

APIs with No authentication are the easiest to get started with - you can begin making requests immediately. If you’re prototyping or learning, these are ideal. APIs requiring apiKey or OAuth offer more features but require registration and setup.

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Check HTTPS support

For production applications, prefer APIs with HTTPS support for security. This is especially important if you’re handling sensitive data.

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Verify CORS compatibility

If you’re building a client-side web application, you need an API with CORS: Yes. Without CORS support, the API can only be called from server-side code.

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Read the documentation

Always review the official API documentation (linked in the API column) to verify:
  • Rate limits and usage quotas
  • Response formats (JSON, XML, etc.)
  • Available endpoints and features
  • Free tier limitations
Here are some common use cases and recommended APIs:

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Random content generation

  • Axolotl (Animals) - Axolotl pictures and facts, No auth, HTTPS, No CORS
  • Cat Facts (Animals) - Daily cat facts, No auth, HTTPS, No CORS
  • Dogs (Animals) - Dog pictures from Stanford dataset, No auth, HTTPS, Yes CORS
  • Bored (Development) - Random activities to fight boredom, No auth, HTTPS

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Data enrichment

  • IPstack (APILayer) - Locate visitors by IP address, apiKey, HTTPS
  • Agify.io (Development) - Estimate age from first name, No auth, HTTPS, Yes CORS
  • Genderize.io (Development) - Estimate gender from first name, No auth, HTTPS, Yes CORS

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External integrations

  • GitHub (Development) - Repository and user data, OAuth, HTTPS, Yes CORS
  • Trello (Business) - Boards and project management, OAuth, HTTPS
  • Gmail (Business) - Email access and management, OAuth, HTTPS

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Cryptocurrency and finance

  • CoinGecko (Cryptocurrency) - Crypto prices and market data, No auth, HTTPS, Yes CORS
  • CoinDesk (Cryptocurrency) - Bitcoin Price Index, No auth, HTTPS
  • Exchangerate.host (Currency Exchange) - Free exchange rates, No auth, HTTPS

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Location and maps

  • Nominatim (Geocoding) - OpenStreetMap geocoding
  • IP geolocation APIs - Convert IP addresses to locations

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Testing APIs

Many APIs in the directory include a “Run in Postman” button that provides a pre-configured Postman collection. This lets you test endpoints immediately without writing code.

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Next steps