9 skills · 4 categories
Claude Code skills for OpenAPI and REST
API skills for REST design, OpenAPI specs that generate clients, contract testing, versioning, RFC 9457 error responses and documentation developers can follow on the first try.
Start with these
- 1
OpenAPI Codegen
Generated clients that stay in sync with the spec
Claude picks one generator per language from a decision table, fixes the spec first so names and types come out clean (operationIds, named schemas, discriminators, accurate required lists), pins tool versions behind a single gen script, and adds CI gates for lint, oasdiff breaking changes, regeneration drift and consumer typechecks. A bundled checker flags spec problems before any code is generated.
- 2
REST API Design
Predictable endpoints, machine-readable errors, safe retries
Claude designs endpoints spec-first instead of improvising handlers. It matches your existing conventions, picks exact status codes, returns RFC 9457 problem documents, paginates with stable cursors, adds Idempotency-Key and ETag support where retries or concurrent edits happen, and runs oasdiff so a renamed field never ships as a silent breaking change.
- 3
API Versioning and Deprecation
Change public APIs without surprising a single client
Claude classifies every API change as additive or breaking before it ships, turns most breaks into expand-and-contract steps, and picks URL or date-based versioning only when needed. Deprecations get RFC 9745 and RFC 8594 headers, OpenAPI markers, per-client usage telemetry, a migration guide, brownouts, and a 410 Gone after sunset, with removal gated on data and your confirmation.
All 9 OpenAPI and REST skills
Grouped by category. Each card opens the full playbook, example prompts and install commands.
Backend & APIs 5
OpenAPI Codegen
Generated clients that stay in sync with the spec
Claude picks one generator per language from a decision table, fixes the spec first so names and types come out clean (operationIds, named schemas, discriminators, accurate required lists), pins tool versions behind a single gen script, and adds CI gates for lint, oasdiff breaking changes, regeneration drift and consumer typechecks. A bundled checker flags spec problems before any code is generated.
REST API Design
Predictable endpoints, machine-readable errors, safe retries
Claude designs endpoints spec-first instead of improvising handlers. It matches your existing conventions, picks exact status codes, returns RFC 9457 problem documents, paginates with stable cursors, adds Idempotency-Key and ETag support where retries or concurrent edits happen, and runs oasdiff so a renamed field never ships as a silent breaking change.
API Versioning and Deprecation
Change public APIs without surprising a single client
Claude classifies every API change as additive or breaking before it ships, turns most breaks into expand-and-contract steps, and picks URL or date-based versioning only when needed. Deprecations get RFC 9745 and RFC 8594 headers, OpenAPI markers, per-client usage telemetry, a migration guide, brownouts, and a 410 Gone after sunset, with removal gated on data and your confirmation.
ASP.NET Core APIs
Problem details, fail-closed auth, real integration tests
Claude wires ASP.NET Core APIs so failures are consistent and safe: IExceptionHandler and status code pages produce problem details, a fallback policy requires auth everywhere, options validate on start, and DI scopes are checked at build. Endpoints return TypedResults with owner-filtered EF Core projections, and integration tests run the real pipeline against Postgres in Testcontainers.
gRPC Services
Safe proto evolution and calls that always have deadlines
Claude designs protobuf APIs with per-RPC request and response messages, reserved field numbers and versioned packages, then gates every change with buf lint and buf breaking. Server code propagates deadlines, returns precise status codes with google.rpc error details, retries only idempotent calls, and fixes the classic HTTP/2 problem of one client pinning all traffic to one pod.
Testing 2
API Testing
Prove every endpoint's contract, including who can't call it
Claude picks one API test format for the repo, builds an endpoint-by-case matrix that includes validation errors, expired tokens, wrong roles and cross-tenant access, and writes self-contained tests that create their own data. Responses are checked against the OpenAPI schema plus the fields each case is about, and CI runs the suite against a fresh container with JUnit output and service logs.
Contract Testing
Catch breaking API changes before either side deploys
Claude picks between consumer-driven Pact contracts and provider-owned OpenAPI checks based on who the consumers are, then wires the full loop: consumer tests with type matchers, provider verification with named states, a broker, can-i-deploy before every deploy and record-deployment after. Breaking API changes fail a pipeline instead of a production release.
Install
Every OpenAPI and REST skill in one command
Installs into ~/.claude/skills/. Add --project after -- to install into the current repository.
curl -fsSL https://claudeskills.page/install.sh | sh -s -- openapi-codegen rest-api-design api-versioning-deprecation aspnet-core-apis api-testing contract-testing api-documentation airtable-api grpc-services OpenAPI and REST skills FAQ
What is the best Claude Code skill for OpenAPI and REST?
Start with OpenAPI Codegen: Generated clients that stay in sync with the spec. Then add REST API Design and API Versioning and Deprecation, which cover the next most common OpenAPI and REST requests.
How do I install all 9 OpenAPI and REST skills at once?
Pass every name to the installer in one command: curl -fsSL https://claudeskills.page/install.sh | sh -s -- openapi-codegen rest-api-design api-versioning-deprecation aspnet-core-apis api-testing contract-testing api-documentation airtable-api grpc-services. Add --project to install them into the current repository's .claude/skills/ folder so your team gets them too.
Do these OpenAPI and REST skills work outside Claude Code?
Yes. Each skill uses only the portable Agent Skills frontmatter, so the same folder works on claude.ai, through the Claude API and in the Agent SDK. Skills that run bundled scripts need an environment with code execution.