Generate OpenAPI / Swagger specification
AI writes complete, valid OpenAPI YAML spec from your endpoint list.
Generate OpenAPI / Swagger specification
River's OpenAPI Specification Generator creates complete, valid OpenAPI 3.0 YAML specs from your endpoint descriptions. You provide endpoints, methods, and parameters, and the AI writes comprehensive specifications including paths, request/response schemas, authentication, error responses, and examples. Whether you're documenting APIs, generating client SDKs, or enabling API testing, you get professional OpenAPI specs ready for Swagger UI and code generation tools.
Unlike manual specification writing, we create structured, validated specs. The AI understands OpenAPI conventions (proper schemas, reusable components, correct data types, example values), follows REST best practices, and generates specs compatible with OpenAPI 3.0 standard. You get machine-readable API documentation that integrates with the OpenAPI ecosystem.
This tool is perfect for backend developers documenting APIs, teams using API-first development, organizations standardizing API specs, and developers needing Swagger documentation. If you have APIs without formal specs, or if manual OpenAPI writing feels tedious, this tool helps. Use it to create specifications that power documentation, testing, and SDK generation.
What Makes OpenAPI Specs Effective
OpenAPI specifications succeed when they accurately describe APIs and enable tooling. Effective specs include all endpoints with proper HTTP methods, complete request/response schemas with examples, authentication and security schemes, error response documentation, reusable components for common patterns, and valid YAML syntax. Weak specs have incomplete schemas or invalid structure. Strong specs enable automatic documentation generation, client SDK creation, API testing, and contract validation.
The best OpenAPI specs follow consistent patterns. Use components for reusable schemas (User, Error). Define security schemes once, reference everywhere. Include realistic examples in schemas. Document all required and optional parameters. Specify response codes with descriptions. Use proper data types and formats (date-time, email, uuid). Tag endpoints logically for documentation grouping. This structure makes specs both human-readable and machine-processable.
To improve OpenAPI specs, validate with OpenAPI validators before publishing. Test with Swagger UI (does documentation render correctly?). Generate client SDKs (do they work?). Keep specs synchronized with actual API behavior. Version your specs with API versions. Use description fields generously (explain what things do). Include working examples (help developers understand). Remember: OpenAPI spec is contract between API provider and consumers. Clear, accurate, complete specs enable successful API integration.
What You Get
Complete OpenAPI 3.0 specification in YAML
All endpoints with request/response schemas
Authentication and security definitions
Reusable components and examples
Valid, tool-compatible specification
Ready for Swagger UI and SDK generation
How It Works
- 1List API endpointsProvide endpoints, methods, parameters, and descriptions
- 2AI generates OpenAPI specOur AI creates complete YAML specification in 5 to 7 minutes
- 3Review and validateCheck spec, add specific details, validate YAML
- 4Use with toolingImport to Swagger UI, generate SDKs, enable API testing
Frequently Asked Questions
Is this OpenAPI 2.0 (Swagger) or 3.0?
OpenAPI 3.0 (the current standard). OpenAPI 3.0 replaced Swagger 2.0 and added better support for complex schemas, callbacks, links, and more. Most modern tools support OpenAPI 3.0. If you need Swagger 2.0, conversion tools exist.
Can I generate client SDKs from this spec?
Yes! OpenAPI specs work with code generators like OpenAPI Generator, Swagger Codegen, and language-specific tools. Once you have valid spec, you can generate client libraries for JavaScript, Python, Java, Go, and many other languages automatically.
How do I keep OpenAPI spec synchronized with actual API?
Best practice: generate specs from code annotations or use spec-first development. Some frameworks (FastAPI, NestJS) generate OpenAPI specs automatically from code. Alternatively, use contract testing to verify API matches spec. Manual specs require discipline to keep updated with code changes.
Should I include examples in the spec?
Yes, absolutely. Examples in request/response schemas help developers understand expected data format. They also improve generated documentation and enable better testing. Good examples are realistic, show typical use cases, and include edge cases where helpful.
What's the difference between OpenAPI and REST API documentation?
OpenAPI is machine-readable specification format. REST API documentation is human-readable explanation. OpenAPI specs power tools that generate both documentation and code. You can have OpenAPI spec generate beautiful documentation automatically using Swagger UI, Redoc, or similar tools. Spec is source of truth.
What is River?
River is an AI-powered document editor that helps you write better, faster. With intelligent writing assistance, real-time collaboration, and powerful AI tools, River transforms how professionals create content.
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