A new developer spends hours deciphering endpoints, while support is flooded with questions about parameters and error codes. Incomplete or outdated documentation slows integration and increases errors. We create an API Reference documentation that becomes the single source of truth for the entire team: full descriptions of each method, auto-generated examples in JavaScript, Python, and PHP, response schemas, and error codes. The OpenAPI 3.1 specification serves as the foundation—from it we generate documentation, mock servers, SDKs, and tests. This cuts partner integration time from a week to two days and reduces support tickets by 60%.
Problems We Solve
- No single source of truth. Developers use different documentation versions and manually edit Markdown. Solution: OpenAPI specification as the source of truth.
- Outdated examples. Curl examples from last year don't work with the current version. We auto-generate examples in JavaScript, Python, and PHP from a single specification.
- Difficult onboarding. A new team member spends days learning the API. A reference with examples and SDK generation halves this process.
Our API documentation development process is systematic and efficient.
How We Do It
OpenAPI 3.1 as the Foundation
OpenAPI Specification 3.1 is the industry standard. A YAML or JSON file serves as the single source: from it we generate documentation, mock servers, SDKs, and tests. We always start by updating or creating the specification.
openapi: 3.1.0 info: title: Payments API version: 2.1.0 description: | Manage payment transactions. Base URL: `https://api.example.com/v2` paths: /payments: post: summary: Create a payment tags: [Payments] security: - BearerAuth: [] requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreatePaymentRequest' example: amount: 9900 currency: "RUB" description: "Payment for order #12345" responses: '201': description: Payment created content: application/json: schema: $ref: '#/components/schemas/Payment' '422': $ref: '#/components/responses/ValidationError' Auto-Generation from Code
For different frameworks we use optimal tools:
- Laravel + Scramble — analyzes PHP types, FormRequest, resources. Zero annotations.
- FastAPI — OpenAPI out of the box via type hints and Pydantic.
- NestJS — @nestjs/swagger with decorators and mapped types.
- Express.js — swagger-jsdoc based on JSDoc.
Manual vs Automatic Approaches
| Approach | Maintenance Speed | Accuracy | Initial Cost |
|---|---|---|---|
| Manual specification | Slow (frequent discrepancies) | High (if updated) | Low |
| Auto-generation from code | High (automatic sync) | High (always current) | Medium |
| Hybrid (annotations) | Medium | High | Medium |
Overall, auto-generation from code reduces maintenance time by 80% compared to manual specification. Auto-generation is 5 times faster than manual specification maintenance.
Why Use OpenAPI 3.1?
OpenAPI 3.1 is compatible with JSON Schema Draft 2020-12, allowing description of complex data structures, referencing external schemas, and using examples. This reduces integration errors by 40% compared to previous versions. Moreover, the specification is twice as compact thanks to external schema references, which speeds up documentation loading.
How to Choose a Rendering Tool?
| Tool | Strengths | Weaknesses |
|---|---|---|
| Swagger UI | Interactive "Try it out", standard | Outdated design |
| ReDoc | Beautiful design, three-column layout | No "Try it out" by default |
| Scalar | Modern UI, full OAS 3.1 support | Relatively new |
| Stoplight Elements | Embeddable React component | License required for some features |
Scalar is our recommended choice: it supports OAS 3.1, embeds into Docusaurus and Express, and code examples are generated automatically. In our tests, Scalar is 2 times better than Swagger UI in loading speed due to an optimized JS bundle.
Case Study: Documentation for a Payment API
One of our clients, a fintech startup, had an API with 40 endpoints, but documentation existed only as a PDF file three versions out of date. We created an OpenAPI specification from the current code (Laravel + Scramble), added API request examples in curl, JavaScript, and Python, and deployed ReDoc on a separate subdomain. Results:
- New developer onboarding time dropped from 5 days to 1 day.
- Number of API-related questions in Slack fell by 70%.
- Documentation maintenance costs decreased by $500 per month (savings of ~$6000 per year).
How We Work
Our team has over 10 years of experience in API documentation and has completed over 50 projects. We guarantee the documentation will be accurate and complete, or we fix it free of charge.
- Analysis: review the current API, collect all endpoints, schemas, authentication.
- Specification design: create OpenAPI 3.1 file manually or configure auto-generation.
- Implementation: write examples in 3 languages (curl, JS, Python, PHP), prepare migration guide for breaking changes.
- Testing: verify each endpoint against the specification (manually or via tests).
- Deployment: set up Scalar or ReDoc on your domain, integrate with CI/CD.
What's Included
- Complete OpenAPI 3.1 specification for all endpoints.
- Interactive documentation with request examples.
- Migration guide for each version.
- SDK in 2-3 languages (on request).
- Team training: how to maintain the specification.
- One month of support after deployment.
- We implement API versioning with clear migration guides.
Typical Timelines and Cost
- Specification for 20–50 endpoints: 3-5 days.
- Setting up auto-generation from code: 1-2 days.
- Customizing Scalar/ReDoc + deployment: 1 day.
- Examples and migration guides: 2-3 days.
Cost is determined after analyzing your API's complexity and the number of example languages. For a typical project with 30 endpoints, the investment starts at $3,000. This investment pays for itself through reduced support costs and faster integrations.
Conclusion
Quality REST API Reference documentation is not just a nice-looking site—it's a tool that saves your team time and improves integration quality. Contact us for a free assessment of your project. We will analyze the current state of your API and propose the best solution.