Best AI Coding Prompts: Write, Debug & Ship Faster

Write a Secure Authentication Function in [Language]

Act as a security-first senior engineer.

Write a secure user authentication function in [LANGUAGE/FRAMEWORK]:

Requirements:
- Password hashing: bcrypt, min 12 salt rounds
- Input validation: email regex + password strength (8 chars, 1 uppercase, 1 number, 1 special)
- Rate limiting: 5 failed attempts → 15-min lockout stored in Redis
- JWT: 15-min access token + 7-day refresh token (httpOnly cookie)
- Audit log: IP, user-agent, timestamp, success/failure
- Return: { success, accessToken?, error?, code? }

Debug This Error and Explain the Root Cause

You are an expert debugger.

Analyze this error and fix it:
Error message: [PASTE ERROR]
Stack trace: [PASTE STACK TRACE]
Relevant code: [PASTE CODE]

Respond with:
1. Root Cause — exact reason in 1–2 sentences
2. Trigger — what condition caused this specific occurrence
3. Fix — corrected code with inline comments
4. Prevention — how to avoid this class of bug in future
5. Test case — a unit test that would have caught this

Generate a Full CRUD API with Error Handling in Express

Act as a Node.js / Express backend engineer.

Build a complete CRUD REST API for [RESOURCE]:
- GET /[resource] — paginated (page, limit, sortBy, order)
- GET /[resource]/:id — single item with 404 handling
- POST /[resource] — create with Joi/Zod validation
- PUT /[resource]/:id — full + partial update (PATCH behaviour)
- DELETE /[resource]/:id — soft delete (deletedAt timestamp)

Each route: JWT auth middleware · parameterized DB queries · structured error { error, code, message } · correct HTTP codes (200, 201, 400, 401, 403, 404, 500).

Convert This Class Component to a React Functional Hook

You are a React & TypeScript expert.

Convert this class component to a functional component with hooks:
[PASTE CLASS COMPONENT HERE]

Rules:
- componentDidMount → useEffect with [] dependency
- componentDidUpdate → useEffect with specific deps
- this.state → useState (one hook per logical group)
- class methods → useCallback where passed as props
- Add full TypeScript types for props and state
- Show before AND after with a comment on each change

Write Integration Tests for This API Endpoint

Act as a senior QA engineer specialising in API testing.

Write full integration tests for this endpoint using [Jest + Supertest / Pytest]:
Endpoint: [METHOD] [PATH]
[PASTE ENDPOINT CODE]

Cover:
1. Happy path — 200/201 with expected body
2. Missing required fields — 400 with field-level error
3. Invalid types — 400
4. Unauthenticated request — 401
5. Resource not found — 404
6. Conflict/duplicate — 409
7. Server error simulation — 500

Include beforeAll/afterAll DB setup and teardown helpers.