Backend Review

Backend Review Skill

Review backend code for reliability, performance, and API design.

API Design

RESTful Principles

• Correct HTTP methods (GET, POST, PUT, DELETE)
• Proper status codes
• Consistent response format
• Pagination for list endpoints
• Filtering and sorting support

Error Handling

• Meaningful error messages
• Proper HTTP status codes
• Error responses structured
• Stack traces hidden in production

Database

Queries

• N+1 queries identified and fixed
• Indexes used appropriately
• Transactions for related operations
• Pagination for large result sets
• Query timeouts configured

Data Integrity

• Constraints at database level
• Foreign keys properly defined
• Cascade deletes/deletes considered
• Soft deletes vs hard deletes

Performance

• Connection pooling configured
• Caching for frequently accessed data
• Background jobs for slow operations
• Request timeout configured
• Rate limiting implemented

Reliability

• Graceful shutdown implemented
• Health check endpoints
• Logging structured (JSON)
• Metrics exposed
• Error tracking configured

Security

• Input validation on all endpoints
• Authentication middleware
• Authorization checks
• Rate limiting
• CORS configured properly

Code Structure

Layered Architecture

handlers/  -> HTTP handling, validation
services/  -> Business logic
repositories/ -> Data access

• Handlers thin, services contain logic
• Dependency injection
• Interfaces for external dependencies
• Single responsibility

Error Handling

// ❌ Swallowing errors
if err != nil {
    log.Println(err)
    return nil
}

// ✅ Proper error handling
if err != nil {
    return fmt.Errorf("failed to create user: %w", err)
}

Severity Guide

🚨 Error: Data loss, security vulnerability, crash ⚠️ Warning: Performance issue, anti-pattern 💡 Info: Code quality, maintainability