APIs.io is a directory you can read with your eyes — but the whole point is that you can also read it with code. Behind the website that indexes 8329 providers, 28401 APIs, and 115763 schemas sits a programmable layer that we’ve pulled together into one place: the developer area at apis.io/developer. If you’ve ever wanted to query the catalog from a script, ground an AI agent in real API metadata, or wire discovery into your own tooling, this is the front door.
Here’s everything that’s available.
One contract, three surfaces
The most important thing to understand about the developer area is that the REST API, the MCP server, and the agent skills are all generated from the same OpenAPI contract. They never drift. Learn the resources once and you know all three surfaces — pick whichever one fits how you’re building.
The REST API
The REST API is read-only and open. No signup, no key, every endpoint is a plain GET against https://apis.io/api/v1. Search the whole catalog in one call:
curl "https://apis.io/api/v1/search?q=payments&limit=3"
Scope results with return (apis, providers, or tags) and filter by tags, providers, artifact_types, industry, region, and rating band:
# Messaging APIs from strong+ providers that ship an OpenAPI
curl "https://apis.io/api/v1/search?return=apis&tags=messaging&artifact_types=OpenAPI&band=exemplar,strong"
Drill into a single provider or API, and inline the actual artifact bytes when you want them:
curl "https://apis.io/api/v1/providers/twilio"
curl "https://apis.io/api/v1/apis/twilio:twilio-accounts-api?artifact_types=OpenAPI&include=content"
Providers are slugs (twilio); APIs are provider:api-slug (twilio:twilio-accounts-api). The same contract exposes tags, ratings, and a dozen artifact collections — OpenAPI, AsyncAPI, Postman, Arazzo, JSON Schema, JSON-LD, GraphQL, governance rules, and more.
The MCP server
For AI agents, the catalog is a Model Context Protocol server over Streamable HTTP at https://apis.io/mcp. Point any MCP-capable client at it:
{
"mcpServers": {
"apis-io": {
"url": "https://apis.io/mcp"
}
}
}
It ships 15 curated, read-only tools led by apis_io_search — the power tool for finding APIs, providers, or tags by free text, tag, artifact type, industry, region, and rating band — plus drill-down and taxonomy tools like find_apis/get_api, find_providers/get_provider, and find_industries/find_regions. Your agent can discover and ground itself in real API metadata without you writing a single integration.
Agent skills
Beyond the API, providers across the network publish agent skills — the SKILL.md packages that teach AI coding agents how to operate a product correctly. The skills directory now spans more than a hundred providers and well over a thousand individual skills, all indexed and browsable, with a machine-readable index at /.well-known/agent-skills/index.json.
Plans and rate limits
Version 1 is open and free — anonymous GET requests run on the Free tier, and edge rate limiting keeps the service healthy for everyone. The contract is API-key-ready for the day metered tiers arrive: logging in with your GitHub account gets you a free Starter key, and Pro ($49/mo) and Business ($199/mo) tiers raise your limits and unlock the industries, regions, and ratings endpoints. See Plans for the full table. Until then, be a good citizen: cache where you can, paginate with page + limit, and only request the artifact_types you actually need.
Machine-readable feeds
The developer area isn’t just the API. The whole network is self-describing. Every page exposes an RFC 9727 api-catalog linkset enumerating its machine-readable surfaces, the network ships an APIs.json profile, and there’s an llms.txt written specifically for agents. Indexing, RAG, grounding, and model training are all explicitly permitted under our terms.
Start here
Open the developer area, run the getting-started examples, and you’ll be querying the catalog in a minute — no key, no signup, just APIs all the way down.