# Vendor facets — Hey API. The open-source TypeScript code generator for OpenAPI (SDKs, types,
# Zod/Valibot schemas, TanStack Query hooks, 20+ plugins). The headline: it reaches one pointer,
# sdk_count_1, and only when a provider publishes the output as its own SDK. Most runs happen
# inside consumers' codebases, where nothing reaches the provider's surface.
vendor: hey-api
name: Hey API
website: https://heyapi.dev
areas:
- sdk-generation
registry_keys: []
rubric_schema_version: 0.22.0
generated: '2026-09-25'
features_refreshed: '2026-09-25'
basis: capability
summary: >-
  Hey API generates a TypeScript SDK, types, runtime validators and framework hooks from an OpenAPI. It
  is free, open source and self-run. On the Kin Score it can move only sdk_count_1, and only when the
  provider publishes the generated client as a package and declares it. One language cannot reach sdk_count_3
  (Python is listed as coming soon). Zod and Valibot schemas are not JSON Schema, and the tool leaves
  the contract as it found it. Nothing identifies Hey API output on a provider's surface.
features:
- id: ts-sdk
  name: Typed TypeScript SDK and types
  description: >-
    Generated SDK clients and TypeScript interfaces from an OpenAPI, for Fetch, Axios, Angular, Next.js,
    Nuxt and others.
  source: https://heyapi.dev/
  tier: open-source
- id: validators
  name: Zod and Valibot schemas
  description: Runtime validation schemas generated alongside the client.
  source: https://heyapi.dev/
  tier: open-source
- id: tanstack-plugins
  name: TanStack Query and 20+ plugins
  description: Plugins for TanStack Query hooks, Fastify and other integrations, plus a custom plugin
    API.
  source: https://heyapi.dev/
  tier: open-source
maps:
- feature: ts-sdk
  check: sdk_count_1
  layer: composite
  conditional: true
  condition: >-
    Only when the provider publishes the generated client as a package it maintains. Hey API is mostly
    run by API consumers inside their own apps, and that never counts.
  provider_must: Publish the package and declare it as an SDK entry in apis.yml.
  catalog_pass_rate: 0.148
  facet: developer_ergonomics
  points: 3
  baseline_pass_rate: 0.413
earns_nothing:
- feature: validators
  check: json_schema_present
  why: Zod and Valibot schemas are TypeScript code, not published JSON Schema.
- feature: ts-sdk
  check: sdk_count_3
  why: One language (TypeScript) cannot make three SDKs. Python is listed as coming soon.
- feature: tanstack-plugins
  check: examples_published
  why: Generated hooks are client code, not an example corpus.
out_of_reach:
  checks:
  - cli_present
  - mcp_server
  - documentation_present
  - api_reference_present
  - llms_txt_published
  - agent_skills
  - agent_skill_present
  - postman_present
  - overlay_published
  - contract_present
  note: >-
    The site describes self-hosted generation via a CLI only. It lists no docs, MCP, llms.txt, skill or
    contract-editing output.
unscored_practice:
- feature: validators
  why: Runtime validators derived from the contract are a real client practice that no check reads.
surface:
  developer_ergonomics:
    reachable: 3.0
    total: 42
  agent_readiness:
    reachable: 0
    total: 139
hard_rule: >-
  A model, not a score. Adopting this vendor changes a provider's Kin Score only when the provider publishes
  the resulting artifacts on its own surface; nothing here writes a score, and no sponsorship or partnership
  can.
method: searched
source:
- https://heyapi.dev/
measured:
  cohort:
    method: vendors-catalog.json detections (CNAME / header / URL shape / markup), never a name match
    detected: 0
    in_baseline: 0
  control:
    basis: providers earning contract_present + documentation_present + api_reference_present, minus the
      cohort
    n: 5216
  metric: >-
    cohort_pct / control_pct = mean share of the check's points earned (derived and platform credit weighted),
    x100
  measured_on: '2026-09-25'
  status: 'not measurable: 0 detected customers clear the baseline (need 20)'
simulation:
  simulated_on: '2026-09-25'
  rubric: 0.23.0
  population: providers publishing a contract (contract_present earned), replayable exactly
  providers: 8977
  providers_unreplayable: 987
  providers_moved: 0
  conditional_rows: excluded (they depend on what the API already does)
  composite_lift:
    median: 0.0
    p75: 0.0
    p90: 0.0
    max: 0.0
    mean_among_movers: 0.0
  agent_readiness_lift:
    median: 0.0
    p75: 0.0
    p90: 0.0
    max: 0.0
    mean_among_movers: 0.0
  facet_lift_median_among_movers: {}
  composite_band_moves: {}
  agent_readiness_band_moves: {}
  method: >-
    each provider's own kin/checks file, the vendor's maps at their stated credit, the scorer's composite
    formula; from -> to, nothing written