Browse 500+ free public APIs organized by category. Find the perfect API for your next project — from weather and news to AI and finance.
Every side project starts with the same question: where do I get the data? You have the frontend skills, the deployment pipeline, maybe even a half-decent design. But without real data flowing through your app, it's just a mockup. That's where public APIs come in — and in 2026, there are more free options than ever.
I've spent the last few months cataloging, testing, and categorizing over 505 free public APIs across 12 categories. Whether you're building a weather dashboard, a stock tracker, a social media aggregator, or an AI-powered tool, this guide will point you to the right API and help you avoid the common pitfalls.
You can browse the full searchable directory in our Public API Directory, but here's a curated walkthrough of the best APIs by category, plus practical advice on authentication, rate limits, and choosing the right API for your project.
The API economy has exploded. Companies realized that letting developers build on their platforms creates network effects money can't buy. The result: thousands of APIs with generous free tiers that give you access to real-time weather data, financial markets, machine learning models, geolocation services, and more — all without spending a dollar.
But "free" doesn't mean "simple." Free APIs come with trade-offs: rate limits, authentication requirements, usage caps, and varying levels of documentation quality. Knowing how to navigate these trade-offs is what separates a weekend project that works from one that hits a wall at 2 AM on Sunday.
The finance category is one of the richest in our directory, with 70 APIs covering everything from stock prices to cryptocurrency rates.
Alpha Vantage remains a go-to choice for stock market data. Their free tier gives you access to real-time and historical stock prices, forex rates, and technical indicators. The rate limit is 25 requests per day on the free plan, which is enough for personal dashboards but tight for anything production-grade. Authentication is via a simple API key.
CoinMarketCap dominates the crypto space. Their free tier covers 10,000 requests per month with access to the latest cryptocurrency listings, quotes, and market cap data. If you're building a crypto portfolio tracker, this is probably where you start.
Stripe isn't just a payment processor — their API is one of the most well-documented in the industry. The test mode gives you full API access without processing real payments, making it perfect for building e-commerce prototypes. OAuth2 authentication, excellent SDKs in every major language, and genuinely helpful error messages.
With 70 AI/ML APIs in our directory, this category has grown faster than any other in the past two years.
OpenAI's API needs no introduction. While the free tier is limited, their pay-as-you-go model is affordable for experimentation. Text generation, image creation, embeddings, and speech recognition — all through a single, well-designed REST API. Bearer token authentication keeps things simple.
Hugging Face Inference API is the hidden gem of this category. Free tier gives you access to thousands of open-source models for text classification, translation, summarization, image generation, and more. Rate limits are generous for prototyping, and you can switch between models with a single parameter change.
Replicate offers a similar model-hosting approach with a free trial. Run open-source AI models via API without managing any infrastructure. Great for testing different models before committing to one.
The data category houses 70 APIs that serve structured datasets from government agencies, research institutions, and data aggregators.
NASA's Open APIs are genuinely delightful. Astronomy Picture of the Day, Mars Rover photos, near-Earth asteroid tracking, satellite imagery — all free with a simple API key. Rate limit is 1,000 requests per hour, which is more than generous.
World Bank Open Data provides socioeconomic indicators for every country on the planet. GDP, population, literacy rates, CO2 emissions — decades of data accessible via a clean REST API. No authentication required at all.
OpenFDA gives you access to U.S. drug adverse events, product recalls, and food enforcement data. If you're building anything health-tech adjacent, this is a goldmine of structured, reliable data.
Our directory includes 59 geo APIs for mapping, geocoding, routing, and location intelligence.
Mapbox offers one of the most developer-friendly mapping experiences. Their free tier includes 50,000 map loads per month, geocoding, directions, and static map images. The JavaScript SDK is excellent, and the documentation is some of the best in the industry.
OpenStreetMap's Nominatim provides free geocoding (converting addresses to coordinates and vice versa). No API key required, though they ask for a reasonable usage policy. Perfect for hobby projects that need geocoding without a billing account.
IP-API gives you geolocation data from IP addresses — country, city, latitude, longitude, ISP, and timezone. The free tier handles 45 requests per minute with no authentication. Dead simple to integrate.
With 65 media APIs, this category covers everything from movie databases to image processing.
TMDB (The Movie Database) is the community-driven movie and TV database that powers countless apps. Free API key gets you access to metadata, images, trailers, and ratings for millions of titles. Rate limit is about 40 requests per 10 seconds — more than enough for most applications.
Spotify Web API lets you search the catalog, get track audio features, manage playlists, and access personalized recommendations. OAuth2 authentication is required, but the documentation walks you through every step. The audio features endpoint (danceability, energy, tempo) enables some genuinely creative projects.
Unsplash API provides access to over 3 million high-resolution photos, all free to use. The free tier allows 50 requests per hour. If your project needs beautiful imagery without licensing headaches, this is the answer.
We catalog 65 social APIs and 65 communication APIs — the building blocks of connected applications.
Twilio is the heavyweight for SMS, voice, and messaging. Their free trial gives you a phone number and enough credits to test SMS sending, voice calls, and WhatsApp messaging. The API design is a masterclass in RESTful architecture.
Discord API lets you build bots, manage servers, and integrate with the platform that has become the de facto community hub for developers. Free to use with bot token authentication. The WebSocket gateway for real-time events is well-documented.
SendGrid (now part of Twilio) offers 100 emails per day on the free tier. Enough for transactional emails in a side project. API key authentication, straightforward JSON payloads, and delivery tracking built in.
The 65 cloud APIs in our directory cover everything from serverless functions to object storage.
Cloudflare API gives you programmatic control over DNS, Workers, R2 storage, and more. If you're already using Cloudflare (and in 2026, who isn't?), the API lets you automate everything from cache purging to firewall rule management.
GitHub API is essential for any developer tool. Access repositories, issues, pull requests, and user profiles. The REST API handles 5,000 requests per hour with a personal access token, and the GraphQL API lets you fetch exactly the data you need in a single request.
Vercel API rounds out the trio, letting you manage deployments, domains, and environment variables programmatically. Useful for building deployment dashboards or CI/CD integrations.
Our directory lists 65 dev-tools APIs designed specifically for developer workflows.
GitHub Gist API lets you create, read, and manage code snippets programmatically. Perfect for building code-sharing features into your app.
npm Registry API provides package metadata, download counts, and dependency information for the entire npm ecosystem. No authentication required for public data. Great for building dependency analysis tools.
Have I Been Pwned checks email addresses and passwords against known data breaches. The API is free for non-commercial use and invaluable for security-focused projects.
The health (50 APIs) and IoT (50 APIs) categories are newer but growing rapidly.
OpenFDA (mentioned earlier) leads health, while FHIR-compliant APIs from major health systems are opening up access to clinical data in standardized formats.
On the IoT side, ThingSpeak lets you store and retrieve sensor data through a REST API, and PurpleAir provides real-time air quality data from a network of community-maintained sensors.
Not all free APIs are created equal. Here's what to evaluate before committing to one:
AkousaAuthorization header.Every free API has limits. The question is whether those limits fit your use case:
Pro tip: Cache aggressively. A weather API that allows 1,000 requests per day is actually unlimited if you cache responses for 15 minutes. Most weather data doesn't change faster than that anyway.
This might be the most underrated factor. A well-documented API with a 500 req/day limit will save you more time than a poorly documented one with unlimited access. Look for:
Check if the API has a status page. Search for "[API name] outage" on social media. A free API that goes down every weekend is worse than one with tighter rate limits but 99.9% uptime.
Before writing a single line of integration code, test the API manually. You need to understand the response format, verify that the data meets your needs, and confirm that authentication works as documented.
Our API Tester tool lets you do exactly this — build requests, set headers and authentication, send them, and inspect responses — all in your browser without installing anything. It supports GET, POST, PUT, PATCH, and DELETE methods, custom headers, request bodies, and saves your history so you can iterate quickly.
Here's a practical workflow:
This approach saves hours of debugging later. I can't count the number of times I've discovered an API returns data in a completely different format than the docs suggest — and catching that before writing code is always worth the five minutes.
After integrating dozens of APIs across various projects, here are the patterns that have saved me the most headaches:
Never call an API directly from your components or business logic. Create a thin wrapper that handles authentication, error formatting, and response parsing. When (not if) you need to switch providers, you'll only change one file.
Free APIs have rate limits, and you will hit them. Implement retry logic with exponential backoff: wait 1 second, then 2, then 4, then 8. Most rate limits reset within a minute, so aggressive retries just waste your quota.
Store API responses in memory, localStorage, or a database depending on freshness requirements. Stock prices need real-time data. Country population data doesn't change in an hour. Match your cache TTL to how fast the underlying data actually changes.
Free APIs can shut down, change pricing, or degrade without notice. For critical features, identify a backup API in the same category. Our Public API Directory makes this easy — filter by category and compare authentication methods and rate limits side by side.
Track how many requests you're making per day and per month. Set up alerts before you hit limits. There's nothing worse than your app silently breaking because you exhausted your free tier on day 15 of the month.
What I've covered here is just a sample. The complete Public API Directory has 505+ APIs across 12 categories, each with authentication details, rate limits, CORS support information, pricing tiers, and direct links to documentation. You can filter by category, search by name, and save your favorites for quick access.
Whether you're a student building your first portfolio project, a freelancer prototyping for a client, or a senior developer evaluating integrations for a production system — the right API is probably already in the directory. Go find it, test it with the API Tester, and build something worth showing off.