How do you document your Next.js project?

Documenting a Next.js project effectively is often overlooked, but it’s crucial for maintainability, onboarding new team members, and scaling your application over time. From my experience working on multiple production-grade Next.js apps, good documentation isn’t just about writing a README file—it’s about creating a living, accessible resource that reflects the architecture, conventions, and nuances of your project.

Here’s a detailed breakdown of how I approach documenting Next.js projects, including practical tips, common pitfalls, and examples you can adapt.

Why Documentation Matters in Next.js Projects

Next.js projects can quickly become complex, especially when you start mixing server-side rendering (SSR), static site generation (SSG), API routes, and client-side logic. Without clear documentation, developers waste time figuring out routing conventions, data fetching strategies, or deployment setups. Good docs reduce cognitive load and help maintain consistency across the codebase.

In interviews, I often emphasize that documentation is part of the developer experience. It’s not just for others but also for your future self. When you revisit a project after months, well-structured docs save hours of guesswork.

Core Areas to Document in a Next.js Project

Next.js has some unique features and conventions, so your documentation should cover these key areas:

• Project Overview: What the app does, its architecture, and key technologies.
• Folder Structure: Explain the purpose of important directories like pages/, components/, public/, and api/.
• Routing: Next.js uses file-based routing, but dynamic routes and catch-all routes can be confusing.
• Data Fetching Methods: Document when and why to use getStaticProps, getServerSideProps, or client-side fetching.
• API Routes: If you use Next.js API routes, explain their structure and usage.
• Styling Approach: Whether you use CSS Modules, styled-jsx, Tailwind CSS, or another method.
• Environment Variables: How to configure and use them securely.
• Build & Deployment: Steps to build, test, and deploy the app.
• Common Patterns & Conventions: Any custom hooks, context providers, or state management patterns.
• Testing: How to run tests and what frameworks are used.

Real-World Example: Documenting Data Fetching Strategies

One area that trips up many developers is Next.js’s multiple data fetching methods. Here’s how I document it in a typical project README or docs site:

## Data Fetching in Next.js

Next.js supports three main ways to fetch data:

1. `getStaticProps` (Static Generation)
   - Runs at build time.
   - Use for pages where data changes infrequently.
   - Great for performance and SEO.
   - Example:
     ```js
     export async function getStaticProps() {
       const res = await fetch('https://api.example.com/posts');
       const posts = await res.json();
       return { props: { posts } };
     }
     ```

2. `getServerSideProps` (Server-Side Rendering)
   - Runs on every request.
   - Use when data must be fresh or user-specific.
   - Slower than static generation but necessary for dynamic content.
   - Example:
     ```js
     export async function getServerSideProps(context) {
       const { userId } = context.params;
       const res = await fetch(`https://api.example.com/user/${userId}`);
       const user = await res.json();
       return { props: { user } };
     }
     ```

3. Client-side Fetching
   - Use React hooks like `useEffect` or libraries like SWR/React Query.
   - Good for user interactions or data that updates frequently.
   - Example:
     ```js
     import useSWR from 'swr';

     function Profile() {
       const { data, error } = useSWR('/api/profile', fetcher);
       if (error) return <div>Failed to load</div>;
       if (!data) return <div>Loading...</div>;
       return <div>Hello, {data.name}</div>;
     }
     ```

This kind of explanation helps developers understand trade-offs and pick the right method for their use case.

Best Practices for Documenting Next.js Projects

• Use a Dedicated Docs Folder or Site: For medium to large projects, a docs/ folder or a tool like Storybook or Docusaurus can keep docs organized and easy to navigate.
• Keep README Focused: Your README should give a high-level overview, setup instructions, and how to run the app locally. Avoid dumping all details here.
• Document Code with Comments: Use JSDoc or inline comments for complex components, especially custom hooks or utilities.
• Include Examples: Real code snippets showing how to use components or APIs help reduce confusion.
• Update Docs Alongside Code: Outdated docs are worse than no docs. Make documentation part of your pull request checklist.
• Explain Environment Variables Clearly: Document what each variable does, default values, and security implications.
• Use Diagrams for Architecture: Visuals showing data flow, SSR vs SSG, or API interactions can clarify complex concepts.

Common Mistakes Developers Make When Documenting Next.js

• Assuming Everyone Knows Next.js: Not everyone is familiar with Next.js conventions. Explaining file-based routing or data fetching methods prevents confusion.
• Overloading README: Dumping everything in README makes it hard to find important info.
• Ignoring API Routes: Since Next.js allows backend code in the same repo, documenting API routes and their contracts is often neglected.
• Not Documenting Deployment: Next.js supports many deployment targets (Vercel, Netlify, custom servers). Not documenting your chosen approach causes onboarding friction.
• Skipping Versioning: If your docs don’t track changes with code versions, they quickly become stale.

Performance Considerations in Documentation

While documentation itself doesn’t affect runtime performance, explaining performance implications of Next.js features is valuable. For example, you should document:

• When to use static generation vs server-side rendering to optimize load times.
• How incremental static regeneration (ISR) works and when to use it.
• How to avoid client-side fetching pitfalls that cause unnecessary re-renders or slow UX.

Including these notes helps developers make informed decisions that impact app speed and scalability.

Security Considerations to Document

Next.js projects often handle sensitive data, especially when using API routes or server-side rendering. Documenting security best practices is crucial:

• Environment Variables: Never commit secrets to the repo. Use `.env.local` files and explain how to manage them securely.
• API Route Authorization: Document how authentication and authorization are handled in API routes.
• Data Validation: Explain where and how input validation happens to prevent injection attacks.
• Content Security Policy (CSP): If applicable, document how CSP headers are configured to prevent XSS.

Interview Tips: Talking About Next.js Documentation

When asked about documenting your Next.js project in an interview, focus on:

• How documentation improves team collaboration and reduces onboarding time.
• Specific examples of what you document and why (e.g., data fetching, routing).
• How you keep docs up to date and integrate them into your development workflow.
• Mention tools you use like Markdown, Storybook, or automated doc generation.
• Discuss trade-offs, like balancing detail with readability.

Sharing a story about a time poor documentation caused bugs or delays—and how you fixed it—makes your answer stand out.

Practical Production Scenario: Documenting a Multi-Tenant Next.js App

Imagine you’re working on a SaaS app with multi-tenant support. Your documentation should cover:

• How tenant routing works (e.g., subdomains or path prefixes).
• Data fetching strategies that respect tenant boundaries.
• API route security and tenant isolation.
• Deployment steps that include environment variable setup for different tenants.
• How to add new tenants or customize tenant-specific UI.

Without this, new developers might accidentally break tenant isolation or deploy misconfigured environments.

Comparison: Documenting Next.js vs Other React Frameworks

Aspect	Next.js	Create React App (CRA)	Gatsby
Routing	File-based routing, dynamic routes, API routes	Manual routing with React Router	File-based routing with GraphQL data layer
Data Fetching	SSR, SSG, ISR, client-side	Client-side only	Static generation with GraphQL
Documentation Focus	Explain SSR/SSG, API routes, deployment targets	Focus on routing and client state management	Focus on GraphQL schema and static queries
Deployment	Supports serverless, static, hybrid	Static hosting only	Static hosting optimized

Documenting Next.js projects requires extra attention to server-side concepts and deployment nuances compared to purely client-side React apps.