The open-source API catalog for AI agent builders.
Discover 800+ production-ready APIs across 105 categories, organized into 15 human-friendly capability groups. Build your agent's toolkit visually, or let your agents discover tools programmatically through our free API.
🔗 Live Site · 📖 API Docs · 🛠️ Contribute
If you're building AI agents, you face the same problem everyone does: which APIs should your agent use?
There's no central place to discover, compare, and assemble the right tools. You end up Googling, reading blog posts, and defaulting to whatever you've heard of. Your agent that needs to process payments in Africa ends up using Stripe when Paystack or Flutterwave would be 10x better.
AgentStack fixes this. Every API is categorized, described in plain English, and tagged with free-tier availability. Use the visual builder to assemble a stack, or hit our API to let your agents discover tools themselves.
🧠 Visual Agent Builder — Drag-and-drop interface to assemble your agent's toolkit. See compatibility scores, cost estimates, and synergy analysis in real time.
🔍 Free API for Agents — Three endpoints your agents can call to discover their own tools. No auth required.
📊 800+ APIs Cataloged — Every entry verified, described in plain English, with free-tier info. Covers everything from LLMs to payment processing to satellite imagery.
🤝 Community Driven — Open source. Submit new APIs, fix descriptions, or improve categorization.
No authentication required. Free forever.
GET /api/search?q=payments+africa
GET /api/search?q=voice&free=true
GET /api/search?group=brain&limit=10
Returns matching APIs with name, description, docs URL, free-tier status, group, and category.
GET /api/categories
Returns all 15 capability groups with their subcategories and API counts.
GET /api/recommend?goal=voice+agent+that+takes+payments
GET /api/recommend?goal=research+assistant+with+web+search&free=true
Describe what your agent needs to do in plain English. AgentStack returns a recommended stack with synergy suggestions and security recommendations.
| Group | Icon | What it covers |
|---|---|---|
| Brain | 🧠 | LLMs, NLP, AI infrastructure, translation |
| Eyes | 👁️ | Computer vision, OCR, document processing |
| Creativity | 🎨 | Image generation, video/media, music, 3D |
| Ears | 👂 | Speech-to-text, audio transcription |
| Voice | 🗣️ | Text-to-speech, voice synthesis |
| Research | 🔍 | Search engines, web scraping, news, SEO |
| Money | 💰 | Payments, banking, crypto, stocks, invoicing |
| Navigation | 📍 | Maps, geocoding, satellites, logistics |
| Security | 🔐 | Auth, identity, fraud detection, e-signing |
| Communication | 💬 | Email, SMS, push, voice calls, video |
| Memory | 🗄️ | Databases, vector search, storage, CDN |
| Dev Tools | ⚙️ | CI/CD, containers, serverless, monitoring |
| Business | 🏢 | CRM, HR, legal, e-commerce, scheduling |
| World Data | 🌍 | Weather, health, energy, government data |
| Fun & Social | 🎮 | Social media, gaming, events, education |
git clone https://github.com/stackwyre/agentstack.git
cd agentstack
npm install
npm run devOpen http://localhost:3000 to see the site. The builder is at /builder.
import requests
# Find the right tools for your agent
resp = requests.get("https://agentstack.dev/api/recommend", params={
"goal": "customer support agent with email and chat",
"free": "true"
})
tools = resp.json()["recommendations"]const resp = await fetch(
"https://agentstack.dev/api/search?q=llm&free=true"
);
const { results } = await resp.json();# Use as a tool in your agent framework
def discover_tools(goal: str) -> list:
"""Find the best APIs for a given agent goal."""
resp = requests.get(f"https://agentstack.dev/api/recommend?goal={goal}")
return resp.json()["recommendations"]AgentStack is community-driven. Here's how to help:
- Fork this repo
- Edit
lib/api-database.json - Add your entry to the appropriate category with: name, URL, description (plain English!), and free-tier status
- Open a PR
Same process — find the entry in api-database.json and improve it. Keep descriptions jargon-free and under 140 characters.
Open an issue with the category name and at least 3 APIs that would belong to it.
Open an issue with the API name and what's wrong (dead URL, discontinued, etc.).
Each API entry in the database:
{
"n": "API Name",
"u": "https://docs.example.com",
"d": "Plain English description of what this API does.",
"f": true
}n— Nameu— Documentation URLd— Description (plain English, <140 chars, no jargon)f— Has a free tier (boolean)
MIT — use it however you want.
If AgentStack helped you build something, drop a ⭐ — it helps others find this project.
Built by stackwyre · Got feedback? Open an issue