| API | Website | What it Does | Free Tier | How To Use | Best For | Project Ideas | Difficulty |
|---|---|---|---|---|---|---|---|
| OpenRouter | https://openrouter.ai | Access multiple LLMs from one API | Yes | Get API key → choose model → API call | Multi-model apps | AI assistant, chatbot | Easy |
| Gemini | https://aistudio.google.com | Multimodal AI | Yes | Create API key → SDK/API call | AI apps | Study helper, document Q&A | Easy |
| Groq | https://groq.com | Ultra-fast inference | Yes | API key → completion endpoint | Fast demos | Real-time assistant | Easy |
| Together AI | https://www.together.ai | Open-source model hosting | Yes | API key → model endpoint | Open models | AI playground | Easy |
| OpenAI | https://platform.openai.com | GPT models | Paid/free credits vary | API key → completions | Serious AI products | AI SaaS | Easy |
| Hugging Face | https://huggingface.co | Open ML models | Yes | Use hosted inference API | ML demos | OCR, NLP, vision | Medium |
| Cohere | https://cohere.com | NLP + embeddings | Yes | API key → embeddings/chat | RAG apps | Search engine | Easy |
| Mistral | https://mistral.ai | Open LLMs | Yes | API access | Open AI apps | Coding assistant | Medium |
| Tavily | https://tavily.com | AI search API | Yes | API key → search | RAG systems | AI research assistant | Easy |
| Firecrawl | https://firecrawl.dev | Website crawling for AI | Yes | API → scrape URL | RAG | Website summarizer | Medium |
| Jina AI | https://jina.ai | Embeddings + search | Yes | API call | Search systems | Smart search | Medium |
| Replicate | https://replicate.com | AI model hosting | Yes | Model API | Image/video AI | Image generation | Medium |
| Stability AI | https://stability.ai | Image generation | Yes | API key | Creative apps | AI posters | Easy |
| Fal AI | https://fal.ai | Fast generative AI | Yes | API call | Media generation | AI avatar tool | Medium |
| API | Website | What it Does | Free Tier | How To Use | Best For | Project Ideas | Difficulty |
|---|---|---|---|---|---|---|---|
| AssemblyAI | https://www.assemblyai.com | Speech-to-text | Yes | Upload audio → transcript | Voice tools | Meeting notes | Easy |
| Deepgram | https://deepgram.com | Real-time transcription | Yes | Stream audio | Live systems | Live captions | Medium |
| ElevenLabs | https://elevenlabs.io | Text-to-speech | Yes | API → voice generation | Voice products | Audiobooks | Easy |
| Whisper | https://openai.com/research/whisper | Speech recognition | Free/Open | Local or API | Transcription | Voice notes | Medium |
| API | Website | What it Does | Free Tier | How To Use | Best For | Project Ideas | Difficulty |
|---|---|---|---|---|---|---|---|
| Clerk | https://clerk.com | Auth system | Yes | Install SDK | SaaS auth | Student ERP | Easy |
| Firebase Auth | https://firebase.google.com | Authentication | Yes | SDK integration | MVPs | Chat app | Easy |
| Supabase Auth | https://supabase.com | Auth + DB | Yes | Configure auth | Full stack | Dashboard | Easy |
| Auth0 | https://auth0.com | Enterprise auth | Yes | SDK + config | Secure login | Fintech | Medium |
| Magic Link | https://magic.link | Passwordless login | Yes | SDK | Quick onboarding | Startup apps | Easy |
| API | Website | What it Does | Free Tier | How To Use | Best For | Project Ideas | Difficulty |
|---|---|---|---|---|---|---|---|
| Firebase | https://firebase.google.com | Backend + DB | Yes | SDK | Fast MVP | Student app | Easy |
| Supabase | https://supabase.com | SQL backend | Yes | DB + Auth | SaaS | Analytics dashboard | Easy |
| Appwrite | https://appwrite.io | Backend platform | Yes | Setup cloud/self-hosted | Full stack | CRM | Medium |
| MongoDB Atlas | https://mongodb.com | Database | Yes | Connection URI | NoSQL apps | Social app | Easy |
| Neon | https://neon.tech | Serverless Postgres | Yes | Connect DB | SQL apps | SaaS backend | Easy |
| PlanetScale | https://planetscale.com | MySQL cloud | Yes | Connect DB | Production DB | CRM | Medium |
| PocketBase | https://pocketbase.io | Lightweight backend | Yes | Local setup | Small projects | MVP | Easy |
| API | Website | What it Does | Free Tier | How To Use | Best For | Project Ideas | Difficulty |
|---|---|---|---|---|---|---|---|
| Google Maps | https://developers.google.com/maps | Maps & places | Credits | API key | Location apps | Nearby finder | Medium |
| Mapbox | https://mapbox.com | Mapping | Yes | SDK/API | Geo apps | Logistics tracker | Medium |
| Geoapify | https://geoapify.com | Geolocation | Yes | API key | Places search | Smart map | Easy |
| IPinfo | https://ipinfo.io | User geolocation | Yes | Fetch IP | Personalization | Region content | Easy |
| API | Website | What it Does | Free Tier | How To Use | Best For | Project Ideas | Difficulty |
|---|---|---|---|---|---|---|---|
| Stripe | https://stripe.com | Payments | Yes | SDK/API | SaaS | Subscription app | Medium |
| Razorpay | https://razorpay.com | Payments India | Yes | SDK | Indian apps | College marketplace | Easy |
| CoinGecko | https://coingecko.com | Crypto prices | Yes | Fetch prices | Dashboards | Portfolio tracker | Easy |
| AlphaVantage | https://alphavantage.co | Stock data | Yes | API key | Fintech | Trading dashboard | Medium |
| ExchangeRate | https://exchangerate.host | Currency rates | Yes | Rate API | Utilities | Currency converter | Easy |
| API | Website | What it Does | Free Tier | How To Use | Best For | Project Ideas | Difficulty |
|---|---|---|---|---|---|---|---|
| Open-Meteo | https://open-meteo.com | Weather data | Free | API fetch | Forecasting | Weather app | Easy |
| OpenWeather | https://openweathermap.org | Weather | Yes | API key | Forecasts | Travel planner | Easy |
| Tomorrow.io | https://tomorrow.io | Climate data | Yes | API key | Smart systems | Farming AI | Medium |