What is APIs.io?
APIs.io is a federated, agent-friendly API discovery network. It indexes API providers from across the public internet — their APIs, specifications, schemas, collections, governance rules, operational profiles, and agent surfaces — and exposes each slice of metadata at its own dedicated subdomain site. Everything on the network is open-access, machine-readable, and licensed for search indexing, AI grounding, RAG, and model training.
The network currently indexes 7,800+ API providers, 26,000+ APIs, 110,000+ JSON Schemas, 8,700+ API collections, and millions of individual data points across more than twenty distinct artifact types.
The Specification Ecosystem
Every artifact in the network is described by one or more open specifications. APIs.json is the root — the meta-spec that ties everything else together — and every other spec is declared as a typed property inside a provider’s apis.yml file.
How specifications relate across the APIs.io network — APIs.json at the centre, declaring all artifact types
| Category | Specification | Role | Site |
|---|---|---|---|
| Discovery | APIs.json | Root meta-specification. Every provider is an apis.yml file that declares what specs it publishes and links to all of them. |
apis.io |
| Description | OpenAPI | REST/HTTP API descriptions — the largest catalog on the network | apis.apis.io |
| AsyncAPI | Event-driven, pub-sub, webhook, and streaming API descriptions | asyncapi.apis.io | |
| GraphQL | GraphQL endpoint descriptions, documentation, and reference links | graphql.apis.io | |
| Workflow | Arazzo | Multi-step API workflow specs — chains OpenAPI/AsyncAPI operations into sequences | arazzo.apis.io |
| Schema | JSON Schema | Data model schemas extracted from OpenAPI and AsyncAPI specs | schemas.apis.io |
| JSON-LD | Semantic context files that map API concepts to linked-data vocabularies | json-ld.apis.io | |
| Governance | Spectral Rules | API linting rulesets for validating OpenAPI and AsyncAPI descriptions | rules.apis.io |
| Collections | Open Collection | Open, vendor-neutral collection format (.opencollection.json) |
collections.apis.io |
| Postman Collection | Ready-to-run request collections in Postman format | collections.apis.io | |
| Operational | Plans | API pricing plan profiles (API Commons Plans format) | plans.apis.io |
| Rate Limits | Rate-limit policy profiles (API Commons Rate Limits format) | rate-limits.apis.io | |
| FinOps | Cost and billing profiles aligned with the FinOps Foundation FOCUS framework | finops.apis.io | |
| Agent | Claude Agent Skills | SKILL.md files published by providers — ready for direct AI agent use |
skills.apis.io |
| MCP (Model Context Protocol) | Official MCP server declarations — tools, auth, and connection details | mcp.apis.io |
The Network
Every specification type gets its own subdomain site — a separate Jekyll build on GitHub Pages, each sharing the same provider catalog but presenting its own slice of it.
Search hub, blog, cross-network insights
API provider profiles
Individual API records (OpenAPI)
JSON Schemas
Postman and Open Collections
AsyncAPI event-driven specs
GraphQL specifications
Arazzo API workflow specs
JSON-LD contexts
Spectral governance rulesets
Provider vocabularies
Providers by industry vertical
Providers by sales region
Official Claude Agent Skills
MCP server entries
Event-driven channels (per AsyncAPI channel)
API pricing plans
Rate limit policies
FinOps profiles
API tag index
How It Works
A central build pipeline reads from a set of provider repos at github.com/api-evangelist — Git-versioned APIs.json profiles, one per provider — and emits Jekyll collections into every subdomain site. Each site renders independently from its own collection via GitHub Pages.
Every provider and API page carries:
- A generated prose overview derived deterministically from structured frontmatter
- Schema.org JSON-LD (
Organization,WebAPI,Dataset,CollectionPage) - Open Graph and Twitter Card metadata
- A composite provider rating (0–100, banded Exemplar / Strong / Developing / Thin / Minimal) recomputed on every build
- Cross-page internal links to related providers, industries, regions, and specs
The network also publishes machine-readable feeds at every subdomain: llms.txt, sitemap.xml, and RFC 9727 api-catalog linksets. Start at apis.io/.well-known/api-catalog or apis.io/llms.txt.
Open Access
The APIs.io catalog is licensed for public use including search indexing, AI grounding and RAG, and model training. See apis.io/terms/ for the full terms.
Team & Support
APIs.io is a project led by Kin Lane (API Evangelist) and Steve Willmott (Timewarp Labs). It is built on APIs.json and API Commons, both maintained by Kin and Steve as open infrastructure for the next generation of API discovery.
The upstream provider catalog is maintained at github.com/api-evangelist and the network infrastructure lives at github.com/api-search.
Questions or issues: info@apievangelist.com or open an issue at github.com/api-search/network.