After building APIs for dozens of growing businesses, we've learned what works and what doesn't. Here's a practical guide to creating APIs that can grow with your business.

The foundation: clean endpoints

Your API endpoints should be intuitive and consistent. Here's an example of a well-structured endpoint:

// Good Example
app.get('/api/v1/users/:id', async (req, res) => {
  try {
    const user = await User.findById(req.params.id)
    if (!user) {
      return res.status(404).json({
        success: false,
        message: 'User not found'
      })
    }
    res.json({
      success: true,
      data: user
    })
  } catch (error) {
    res.status(500).json({
      success: false,
      message: 'Internal server error'
    })
  }
})

Error handling that makes sense

Always return clear error messages. Here's our standard error response structure:

interface ErrorResponse {
  success: boolean;
  message: string;
  errorCode?: string;
  details?: {
    field?: string;
    issue?: string;
  }[];
}

// Example usage
const handleError = (error: Error): ErrorResponse => {
  return {
    success: false,
    message: 'Invalid input data',
    errorCode: 'VALIDATION_ERROR',
    details: [
      {
        field: 'email',
        issue: 'Must be a valid email address'
      }
    ]
  }
}

Key lessons

1. Version your API
   • Always include version in URL path
   • Maintain backwards compatibility
   • Communicate changes clearly
2. Cache smartly
   • Use Redis for frequently accessed data
   • Implement proper cache invalidation
   • Monitor cache hit rates
3. Monitor performance
   • Track response times
   • Monitor error rates
   • Set up alerts for anomalies

Real-world impact

"After implementing these patterns, our API response time improved by 60% and error rates dropped to less than 1%."

- Nat, NELKNET Founder

Quick start tips

Want to build better APIs? Start with these basics:

• Use clear naming for your endpoints
• Handle errors gracefully
• Add proper documentation
• Test thoroughly before deployment