The .cursorrules file is your secret weapon for getting consistently high-quality AI suggestions tailored to your project's coding standards.

What Is .cursorrules?

A .cursorrules file in your project root tells Cursor how your project works. Every AI interaction — Tab, Cmd+K, Chat, and Composer — respects these rules. It's like a style guide that the AI actually follows.

Example .cursorrules File

# Project: E-commerce Platform
# Stack: Next.js 14, TypeScript, Tailwind CSS, Prisma, PostgreSQL

## Code Style
- Use functional components with arrow functions
- Prefer named exports over default exports
- Use TypeScript strict mode — no 'any' types
- Use Tailwind classes for styling — never inline styles or CSS modules
- Prefer server components; use 'use client' only when needed

## Naming Conventions
- Components: PascalCase (UserProfile.tsx)
- Utilities: camelCase (formatDate.ts)
- Constants: SCREAMING_SNAKE_CASE
- Database models: singular PascalCase (User, Product, Order)

## Architecture
- API routes go in app/api/
- Shared components in components/ui/
- Page-specific components colocated with their page
- Business logic in lib/ — keep components thin
- Use Zod for all input validation

## Testing
- Write tests for all utility functions
- Use React Testing Library for component tests
- Test user behavior, not implementation details

Why .cursorrules Matters

Without rules, Cursor's AI defaults to generic patterns that may not match your project. With rules:

• Tab completions follow your naming conventions
• Composer creates files in the right directories
• Generated code uses your preferred libraries and patterns
• Consistency across AI-generated and human-written code

Indexing Your Codebase

Cursor automatically indexes your project for codebase-aware suggestions. You can:

• Check indexing status in Settings → Features → Codebase Indexing
• Exclude files/folders with .cursorignore (works like .gitignore)
• Re-index after major changes

Custom Documentation

Add custom docs that Cursor can reference:

1. Settings → Features → Docs
2. Add URLs to your team's documentation, API references, or style guides
3. Reference them in prompts with @docs

This is powerful for internal APIs, proprietary frameworks, or company-specific conventions.

Privacy & Security

Cursor offers a Privacy Mode that ensures:

• Your code is never stored on Cursor's servers
• Code is not used for training AI models
• Only sent to the AI provider for the current request, then discarded

Enable in Settings → Privacy → Privacy Mode. Essential for proprietary codebases.