I have spent my whole career forming opinions about whether an API is any good — not whether the company is valuable or the product is clever, but the narrower, more useful question of whether I can find it, understand it, trust how it behaves, and integrate it without a human beside me filling in what the documentation left out. I made that judgment thousands of times in my head before I finally wrote it down. The result is Kin Score — the API Evangelist rating system: a transparent, machine-readable rubric that scores a provider's public API surface so my sixteen years of opinions about APIs scale, travel, and can be argued with by anyone.

Every input is an artifact the provider actually publishes — an OpenAPI contract with real descriptions and error responses, a change log, documented rate limits, plans a buyer can read without a sales call. There is no panel, no vibes, and no pay-to-play tier that buys a better number. The whole rubric is out in the open, so any provider can see exactly why they scored what they scored and precisely what would move them up.

Two scores, on purpose

Composite quality is what people expect: how complete, transparent, and integration-ready an API is for a human developer — a weighted blend of six always-on facets and {{ all_checks }} individual checks, plus two conditional facets that apply only where they can mean something. Deliberately blunt, because the point is comparability, not a certificate.

Agent readiness is scored separately, because a human developer papers over an enormous amount of API friction that an autonomous agent cannot. Every implicit convention a human silently absorbs — ambiguous errors, undocumented idempotency, prose-only auth — is a place an agent retries blindly, double-charges a card, or hallucinates a payload. It lives on its own axis because a provider can be thin for humans yet ready for agents, or strong for humans yet useless to their agents.

Composite quality bands

A provider's composite score (0–100) maps to one of {{ bands | size }} bands, calibrated against the real distribution of the catalog rather than picked round. The share column is what each band actually holds today.

{%- for b in bands %} {%- endfor %}

What changed in v{{ rubric.schema_version }}. {{ rubric.release_note.body | markdownify | strip_html | strip_newlines | truncate: 620 }} Read the full rubric →

The facets

The composite is a weighted blend of facets, each scored 0–100 from its own checks. The weights decide what "good" means. Six apply to every provider and sum to 100%; two are conditional and apply only where they can mean something — regulatory posture to providers in a regulated industry, open source to providers whose product is itself open source.

{%- for fkey in facet_order %}{% assign f = rubric.facets[fkey] %}{% if f %} {%- endif %}{% endfor %}

Agent readiness separate score

A standalone 0–100 score measuring how safely an autonomous agent can drive the API, mapped to its own {{ abands | size }} bands. A provider can be Thin for humans yet Agent-Ready, or Strong yet Human-Only.

{%- for b in abands %} {%- endfor %}

{{ dims | size }} dimensions feed the score (points each):

{%- for d in dims %}{{ d.label }} {{ d.points }}{% endfor %}

Transparency is the product

The rubric is versioned, all {{ all_checks }} checks are enumerated with the points they award, and the bands are calibrated against the real distribution of what is actually out there rather than picked to flatter anyone. If you disagree with a weight, you can see the weight. If you think a check is wrong, you can see the check. A rating nobody can inspect is just an opinion with better production values, and the industry has enough of those.

Where it runs

The rating system is licensable, and APIs.io is the first company to license it. It runs across the entire APIs.io catalog on every rebuild, shows up in search results and on every provider's page, and is served through the APIs.io API and MCP server so both people and their agents can filter and rank by it.

See it running on APIs.io

Browse live ratings for thousands of API providers, and read the full rubric — every facet, all {{ all_checks }} checks, both scoring axes, and the agent-readiness dimensions with their exact points.

The full rubric & live ratings at APIs.io →

How a provider improves

Every provider is profiled from a public repository in the API Evangelist GitHub organization — github.com/api-evangelist/<provider>. That is where the scored artifacts live, so improving a rating is a normal open-source contribution:

Ask a question — open an issue on the provider's repository.
Add an artifact — submit a pull request with the missing spec, plans, rate limits, or agentic-access contract; the next scoring run picks it up.
Have it done for you — prioritized profiling for $2,500: I audit your surface, add the artifacts, and move you up the queue.

The first two paths are free and always will be — the rubric is open specifically so any provider can climb it on their own.

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