APIs.io API
APIs.io API
Read-only discovery API over the APIs.io catalog of providers, APIs, tags, artifacts, and curated dimensions — free to explore, with synthesis and decision plans above it.
A first-class, read-only discovery API over the APIs.io network.
The catalog is assembled from per-provider repositories and exposed here as the
providers, apis, and tags resources, a first-class collection per
artifact type (/openapis, /asyncapis, /arazzo, /postman, /json-schemas, …),
and a unified /search endpoint that spans them.
Design notes:
- Identifiers.
aidis the stable id. A provider istwilio; an API istwilio:twilio-accounts-api(<provider>:<api-slug>). - Artifacts by reference. API records carry a
propertieslist of artifacts (type+url). By default only references are returned; passinclude=contentto inline an artifact's body. - Selectable artifacts. Use
artifact_typesto return only the artifact types you care about (e.g.OpenAPI,Postman). - Four plans: Explore, Learn, Understanding, Influence. The plans are display names;
the wire values are
free,starter,pro,business, and that is whatx-tier,X-RateLimit-Tierand thetierfield of a 402 carry. Explore (free) is the catalog itself:/search,/providers,/apis,/tags,/tag-groups, the taxonomy dimensions (/industries,/regions,/areas), most artifact-type collections (/openapis,/mcp,/skills,/examples,/json-schemas, …),/playground(the curated no-key starter set — gating it would gate learning to call an API at all), and everything hanging off ONE provider or ONE api, including its own Kin Score and agent-readiness score. Learn is the same surface with your own key and more headroom. Understanding is everything that synthesises across records: the rating data (/ratings,/providers/{slug}/rating,/ratings/rubric), the ranked…/leadersviews,/changes,/cohorts,/capabilities,/insights,/stack,/vcs,/resolve,/enrich, the saved workspace (/me/*), and the high-value security artifact collections (/scopes,/security). Influence is the decision layer:/compare,/gaps,/agent-readiness, the cohort analysis parts, per-company insight depth,/providers/{slug}/investors, the remediation surface,/checks, and bulk dataset pulls (/export). Each operation declares its own plan viax-tier. SendX-API-Keyfor a paid plan; keyless callers get Explore access, metered per IP rather than by a usage plan. A gated call returns 402 Payment Required (not 403 — CloudFront rewrites 403/404). Seex-apis-iofor the full plan / MCP-tool / skill map. - Also an MCP server + Agent Skills. Every operation maps 1:1 to an MCP tool at
https://apis.io/mcp(see each operation'sx-mcp-tool) and, where one exists, an Agent Skill (x-agent-skill). This is the API → MCP → Agent-Skill experience chain.
Tags
Providers
Organizations publishing APIs on the network.
APIs
Individual APIs, each owned by a provider and described by artifacts.
Tags
The tag taxonomy, with network-wide ranking metadata.
Tag groups
The layer between a tag and a facet: sets of tags that demonstrably travel together across providers, computed rather than curated.
Industries
Industry verticals grouping providers across the catalog.
Regions
Geographic regions grouping providers across the catalog.
Areas
The API Evangelist areas taxonomy — curated topic collections (authentication, webhooks, payments, …), each a scored provider index with its own site. Pro.
Synthesis
Decision-grade composites over the catalog — provider comparison, gap analysis, catalog change feed, and recommended-stack design. Pro.
Ratings
The APIs.io API rating system — a 0–100 composite score, five bands, a trend marker, and six weighted facets measuring how complete, governed, and integration-ready each provider's public API surface is. Rubric v0.3.
Cohorts
Any scored population of providers — a tag, industry, region, area, or VC portfolio — with the distribution, rankings, facet scores, and capability matrix that a Trend or Portfolio Report is built from.
Artifact Types
First-class, per-type artifact collections (OpenAPI, AsyncAPI, Arazzo, Postman, JSON Schema, and more). Each path filters and normalizes one artifact type across all providers.
Search
Unified cross-resource search.
Insights
Demand-side intelligence — what ~5,800 companies (Fortune 1000 + API providers) build, buy, and hire for around APIs, data, and AI, derived from job postings, press, and engineering blogs. Discovery is free; per-company depth, gaps, and provider matches are Pro.
Editorial
Story leads mined from catalog movement (owner tier).
Venture Capital
Venture-capital firms as a first-class entity — fund identity plus a network-matched, rated PORTFOLIO GRAPH. Browse firms, walk a fund's portfolio (filter to API providers / by rating band), and follow the reverse edge from a provider to the VCs that back it. Free discovery.
Resolve & Enrich
Agent ergonomics — resolve any identifier (domain, URL, GitHub org) to a provider, and enrich a provider in one call by choosing field groups. Free (the rating and insights enrichment groups are Pro).
Saved Workspace
A Pro dimension — per-user saved searches, lists, and net-new deltas. The same capability the MCP exposes as tools; turns apis.io from stateless lookup into a persistent research workspace. Requires an API key.
Capabilities
The business-capability model: what the catalog's APIs let a business DO, and the quoted contract fragments that evidence each claim.
Your listing
The surface a company uses on its own entry in the catalog: claiming it, asking for the artifacts it is being marked down for not having, correcting what we say, and changing how visible it is. Every operation is a request worked by a person.
Checks
The remediation intake: asking APIs.io to re-profile a listing, and reading where that request stands.
Export
Bulk data export — the license tier above Pro. The whole ratings or providers dataset in one pull, with the attribution string a published figure must carry. Influence plan.
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