What are some of the best practices for API documentation and versioning?

- For API documentation provide real-world request and response examples. This helps users understand the API's behavior. - On API versioning start from the beginning: Even if you're launching the first version, indicate the version. It sets expectations for future changes.

API documentation and versioning are essential to ensure developers can easily understand, implement, and maintain APIs. In terms of documentation, important to use clear language and provide concise content, explanations with examples and code snippets in various programming lang. clear endpoint info, including purpose, params, expected output, should be documented On the versioning front, adhering to Semantic Versioning facilitates clear communication of changes. Incrementing versions based on the nature of changes —major for backward-incompatible changes —minor for backward-compatible additions —patch for bug fixes Combining these practices ensures that API documentation is friendly, informative, and facilitates seamless integration.

Traditionally, it has been said that definition and documentation have to be accomplished before starting coding and implementation and, I agree...mostly. From my experience, the first step would be to define an API Governance framework to leave pristine clear, among others, the following points: - Criteria used to guess which APIs you need to define and how you're going to approach your target market. - Corporate standards and best practices so that all your developers and program/project teams would be fully aligned. - API Lifecycle management, that is, for each of the stages of the API Lifecycle you have to depict how has to do what and how. So, remember, API Governance first is the real key to success. ;-)

The documentation should clearly cover the personas who is going to consume the APIs. The documentation should be comprehensive that the Consumers can use API without any help from the Producers. This reduces the dependency and the friction between producers and consumers of API.

Before you start writing your API documentation, you need to define your target audience and the goals of your API. Who are the users of your API? What are their needs, expectations, and challenges? What are the benefits and value propositions of your API? How do you want to communicate with your users? Answering these questions will help you tailor your documentation to your audience and goals, and avoid unnecessary or confusing information.

The API specification should be a starting point for your API both for design and for documentation. Keep the API spec in a central repository. Also, create a simple API design style guide, and make sure it is used and accepted in your company. It should cover some rules for how you intend to design APIs in your company, e.g. how you name and spell URLs, parameters, how you do paging and versioning etc. It will help with the consistency across all APIs in your API portfolio.

Stripe set a high bar when introducing the 3 column format for API docs, with endpoints listed in the left, details in the middle, and samples on the right. There are now many API doc generators that work off OpenAPI schemas and can generate that 3 column experience.

Using a standard format and style for API documentation is key to ensuring clarity and consistency. In my experience, adopting a widely recognized format like OpenAPI or Swagger helps developers easily understand and interact with your API. A consistent style — clear headings, code examples, and uniform terminology — reduces confusion and improves the user experience. It's also helpful to include error codes, request/response examples, and version history. By keeping your documentation structured and predictable, users can quickly navigate and implement the API, ensuring smoother integrations and minimizing potential errors.

Providing a mechanism for readers to test out the APIs with examples is important. This gives confidence on API integration and enable developers consuming the API to plan their implementation timing accordingly

For simple APIs a well documented API definition (e.g., OpenAPI for REST) should be fine. For more complex stuff, readers may appreciate richer documentation (wiki-like) with diagrams or pictures as a complement to the API definition. For the API usage examples, I prefer tools that do not require coding, e.g., Postman. Anybody can open the collection and start to interact with the API. The main pain is often the authentication and authorization. Even when using a standard such as OAuth, use an example how that works for your API.

Suggestion for the API information section in documentation: 1. Prepare to use: Explain any headers, cookies, and other necessary data in APIs. 2. API Description: For each API, include the following six parts: 2.1. URL 2.2. Method 2.3. Input parameters and their types 2.4. Output parameters and their types 2.5. Example of a request 2.6. Example of responses (200 and otherwise)

Also using a machine-readable API Catalog description using APIs.json can help. This is quite similar to how websites are described using sitemap. xml.

For API documentation, clarity and consistency are key. To get it right, you need to start early in the API lifecycle: - Define the vocabulary for your API, including the business objects and what they mean. Everyone should have a shared understanding of the terms you use to describe your domain. - Also, create a simple API design style guide. It should cover some rules for how you intend to design APIs in your company, e.g. how you name and spell URLs, parameters, how you do paging and versioning etc. It will help with the consistency across all APIs in your API portfolio. With those two definitions in place, write down your API design in OpenAPI specification before you start implementing it.

The key here is to include documentation as a requirement to promote APIs in production environments. You can do this by using API Linting tools (as Spectral validation rules, for example) or relying on some features provided by API Platform vendors.

Regularly updating and versioning your API documentation is essential for keeping users informed and ensuring smooth integrations. In my experience, each time the API evolves—whether through new features, deprecations, or bug fixes—your documentation should reflect these changes. Clearly label the versions and highlight any breaking changes or important updates, so developers know what to expect. Include changelogs for each version to maintain transparency. By keeping the documentation aligned with the API’s latest state, you ensure that users can continue to rely on it effectively and confidently adapt to new versions without confusion.

My suggestion here is to engage your users in the validation processes, once you've done the basic ones. APIs are conceived to be consumed. If possible, involve your target users by engaging them and collaborating with them in almost any validation task...and documentation cannot be an exception.

You need feedback from API consumers early on. Start with the API spec. The OpenAPI spec has a dual purpose, it should serve both as documentation and as a starting point for your implementation. Generate an API prototype out of the OpenAPI spec (can be done automatically) and get some feedback from your targeted API consumers. Only then you should start implementing.

The key point here is to set a standard API versioning scheme (once again, API Governance plays a significant role here) and guarantee that every API in your API Ecosystem is following that standard.

For API versioning, compatibility is the main key. Stay backward compatible in your API releases for as long as possible, since it won't require your API consumers to change their code. But sometimes you have to introduce a breaking change to the API, that is not backward compatible. Then version the API and run the old and new versions in parallel. Obviously, you cannot maintain old versions indefinitely due to maintenance overhead, so you need to sunset your APIs - by communicating with all active API consumers still on that version. Where do you indicate the version? Most people use the path, but a header parameter also works fine.

Calendar-based versioning introduces a simpler versioning semantic when there are frequent breaking changes. It is usually combined with keeping multiple API versions available so that consumers can pin their integration in a certain version until it is deprecated or they need some of the newer features.

(Can't believe I'm wading into an API versioning chat on Monday AM) Query parameters are specific to the application layer and redirects don't belong in this layer. One consideration is that redirecting existing users on a deprecated version based on query parameters can get complicated. This routing should happen in the API Gateway layer and should not be managed in the applications. This approach may hinder the evolvability principle due to a large coordination efforts across multiple application teams to deploy routing.

Following best practices for API versioning ensures smooth transitions and reduces disruptions for users. In my experience, using a clear and consistent versioning strategy, such as semantic versioning (v1.0, v2.0), helps users understand the scope of changes — whether they’re minor updates, feature additions, or breaking changes. Always communicate version updates clearly in your documentation, and maintain support for older versions when possible to allow users time to transition. Deprecating older versions should be handled with clear timelines and guidance. By adhering to these best practices, you ensure a smooth experience for both developers and users, minimizing integration issues.

Best practices for API documentation and versioning include maintaining clear, detailed documentation with consistent naming, comprehensive endpoint descriptions, and examples. Use semantic versioning to track changes, ensure backward compatibility, and provide migration guides. Communicate deprecations and updates clearly to minimize disruptions.

Continue to optimize the documentation based on user feedback. Using a community to reach out and be connected with developers will enable the API to adhere to the needs of consumers today and have a customer backward on any new functionality being released.

Choose a widely recognized and accepted Standard Documentation Format (SDF) for documenting APIs, such as OpenAPI (formerly known as Swagger) or RAML (RESTful API Modeling Language). These formats provide structure and allow for automated generation of documentation.