Best Practices for Designing a Good API

Well‑designed APIs make developers happy and are crucial for product success because they allow applications to easily access another application's data and resources.

APIs enable external applications to use your resources, extend functionality, promote code reuse, and remain platform‑independent, as illustrated by the Google Maps API example.

When modeling data for an API, start by using generic terminology instead of internal business jargon, and structure your data around common concepts such as authors and books to simplify external consumption.

Design resource hierarchies where each URL segment represents a collection or a single resource; for example, https://api.domain.com/authors (collection) and https://api.domain.com/authors/{id}/books (nested collection).

Follow naming guidelines: use American English, avoid spelling errors, prefer simple common words (e.g., delete instead of remove ), keep terms consistent across APIs, and use plural nouns for collections.

Adopt RESTful conventions where each URL represents a resource and standard HTTP verbs map to CRUD operations: GET reads data, POST creates a new resource, PUT updates an existing resource, and DELETE removes a resource.

Implement version control to avoid breaking existing clients. Use minor versions for backward‑compatible changes and major versions for breaking changes. The most common approach is to embed the version in the URI, e.g., https://api.domain.com/v1.0/authors, or use a date‑based version like https://api.domain.com/2020-06-15/authors. Header‑based versioning (e.g., x-api-version: v1) is also possible.

Provide pagination to handle large result sets. Use parameters such as page_token (request), next_page_token (response), and page_size to let clients request a specific page and control the number of items returned. Return an empty next_page_token when no more data is available.

Following these best‑practice guidelines results in APIs that are robust, clear, and easy to integrate with other applications.