What are the best practices for versioning APIs in mobile app development?

1 Why version APIs?

Versioning APIs enables you to evolve your backend without breaking your existing or future app releases. It also helps you to communicate changes, track issues, and manage expectations with your users and stakeholders. Versioning APIs can also improve security, performance, and scalability of your app by allowing you to deprecate or remove outdated or vulnerable endpoints.

3 When to version APIs?

Versioning APIs should be done whenever you make a breaking change to your API contract, such as adding, removing, or renaming fields or parameters, changing the data type or format of fields and parameters, altering the HTTP method, status code, or response body of endpoints, and changing the authentication, authorization, or error handling of endpoints. However, you should avoid versioning APIs for non-breaking changes like adding new endpoints or fields that do not affect existing ones, fixing bugs or improving performance that do not change the API contract, and updating documentation or metadata that do not impact the app logic.

4 How to document APIs?

Documenting APIs is essential for providing clear and accurate information to app developers and users about your API contract, version history, and changelog. It also helps to ensure the consistency, quality, and compliance of your API design and implementation. You can use various tools and formats to document APIs, such as Swagger or OpenAPI which are standards for describing and testing RESTful APIs; Markdown or HTML, which are markup languages for writing and formatting text documents; or Postman or Insomnia, which are applications for creating and managing API requests and responses. To ensure a good workflow it's best to select a tool or format that is easy to use, maintain, and share, while also supporting your API versioning strategy.

5 How to test APIs?

Testing APIs is essential for verifying and validating your API contract, functionality, and performance across different versions, platforms, and scenarios. It also helps to detect and fix issues, bugs, and errors before they can impact your app quality and user experience. To test APIs effectively, you can use unit testing to inspect individual components or functions of your API code, integration testing to examine the interaction and integration of your API code with other components or systems, functional testing to check the functionality and usability of your API endpoints and data, or performance testing to evaluate the speed, reliability, and scalability of your API under various loads and conditions. The best practice is to choose a technique and tool that is suitable, reliable, and comprehensive for your API testing needs and objectives.

6 How to maintain APIs?

Maintaining APIs is essential for ensuring the stability, security, and sustainability of your API and app over time, as well as keeping up with the changing needs and expectations of users and stakeholders. To do so, you should follow the semantic versioning convention, which uses a major.minor.patch format to indicate changes in API versions. Additionally, you should adhere to the backward compatibility principle to ensure new API versions do not break or degrade previous app versions. Furthermore, you should follow a deprecation policy to notify and inform developers and users about the removal or discontinuation of old API versions or endpoints. Ultimately, the best practice is to use a practice and principle that is consistent, transparent, and respectful for your API maintenance and communication.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?