Writing SDK Documentation in English

An SDK — a software development kit — is only as good as its documentation. Engineers who adopt your SDK will judge its quality in the first 15 minutes, based almost entirely on how clear and complete your documentation is. Writing excellent SDK documentation in English is a craft, and it is one that non-native English speakers can absolutely master with the right principles and vocabulary.

Key Vocabulary

Getting started guide A getting started guide (also called a quickstart) is the first piece of documentation a new user reads. Its job is to take the user from zero to a working integration as quickly as possible — typically in under 10 minutes. Example: “The getting started guide should result in a working API call by the end of the first page.”

API reference An API reference is a complete, precise description of every public class, method, function, and type in the SDK. It is the documentation users return to repeatedly during implementation. Example: “The API reference should document every parameter, including optional ones, with their types and default values.”

Code sample A code sample (or code snippet) is a short, functional example that demonstrates how to use a specific feature. Good code samples are self-contained — they should work if copied and pasted with minimal modification. Example: “Each method in the reference should be accompanied by a code sample showing a real-world usage.”

Changelog A changelog is a document that records all notable changes between versions of the SDK — new features, bug fixes, deprecations, and breaking changes. A well-maintained changelog helps developers decide when and whether to upgrade. Example: “Please check the changelog before upgrading from v2 to v3 — there are several breaking changes in the authentication module.”

Deprecation notice A deprecation notice alerts developers that a feature or method will be removed in a future version, giving them time to migrate to the recommended alternative. Example: “The sendRequest() method is deprecated. Please use dispatch() instead, which provides the same functionality with improved error handling.”

Structure of Good SDK Documentation

Overview: A brief explanation of what the SDK does, who it is for, and what problem it solves. Keep this to three or four sentences.

Prerequisites: List what developers need before they start — language version, account credentials, package manager commands.

Installation: The exact commands needed to install the SDK, for each supported package manager.

Getting started: A minimal working example that demonstrates the core use case.

Guides: In-depth tutorials covering common tasks. Each guide should focus on one scenario.

API reference: A complete, auto-generated or manually written reference for all public APIs.

Changelog: A version-by-version record of changes.

Troubleshooting: A FAQ-style section addressing the most common errors and misunderstandings.

Useful Phrases for SDK Documentation

• “Install the SDK using your preferred package manager.”
• “The following example demonstrates how to authenticate and make your first API call.”
• “All methods are asynchronous and return a Promise.”
• “The options parameter is optional. If omitted, the default values will be used.”
• “Throws an AuthenticationError if the provided credentials are invalid.”
• “This method is deprecated and will be removed in version 4.0. Use X instead.”
• “See the API reference for a complete list of available parameters.”
• “The SDK is compatible with Node.js 18 and above.”
• “You will need an API key, which you can obtain from the developer dashboard.”
• “For a full working example, see the sample application in the GitHub repository.”

Writing Style for SDK Documentation

Use second person: Address the reader directly. “You can configure the timeout by passing an options object” is more engaging than “the timeout can be configured.”

Use imperative mood for instructions: “Add the following to your configuration file” rather than “You should add the following.”

Be explicit about types and defaults: “The timeout parameter accepts a number in milliseconds. The default value is 5000.”

Avoid unnecessary qualifiers: “Simply call init()” — the word “simply” implies the task is trivial and can frustrate developers who find it difficult.

Show, then tell: Lead with a code sample, then explain it. Developers scan for code first.

Write for international readers: Avoid idioms, cultural references, and colloquialisms. “This is a piece of cake” means nothing to a developer in Warsaw or Seoul.

Common Writing Mistakes in SDK Documentation

Assuming knowledge: “Configure your environment as usual” — what is usual? Be explicit.

Incomplete error handling in examples: Show how to handle errors in code samples, not just the happy path.

Outdated examples: Code samples that reference deprecated APIs undermine trust. Set up CI to verify that code samples compile.

Passive voice overuse: “The error is returned if the token is invalid” — who returns it? Write: “The method throws an InvalidTokenError if the token has expired.”

Practice Suggestion

Choose any open-source library you use regularly. Find one function or method in its documentation that you think is unclear or incomplete. Rewrite the documentation entry in English, using the vocabulary and style principles from this post. Include a clear description, parameter documentation, a return value description, and a code sample. Compare your version with the original and identify what you improved.