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vanitha natarajan
vanitha natarajan

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Why APIs Work in Dev but Fail in Production

APIs often work perfectly during development and testing.
But once they reach production, issues start appearing — slow responses, timeouts, or unexpected failures.

This usually isn’t caused by bad developers or bad frameworks.
It’s caused by missing production realities.

Let’s break down the most common reasons — and how to avoid them.

1️⃣ Production Traffic Is Very Different from Dev Traffic

In development:

  • Few users
  • Small datasets
  • Minimal concurrent requests

In production:

  • Hundreds or thousands of users
  • Large data volumes
  • Requests hitting the system at the same time

What worked fine with 10 requests can break under 1,000.

What to do

  • Design APIs assuming high concurrency
  • Avoid heavy processing inside request/response cycles
  • Plan for scale early, even if traffic is low today

2️⃣ Databases Become the Bottleneck

Most production API issues are actually database issues.

Common problems:

  • Missing indexes
  • Inefficient joins
  • Fetching more data than needed
  • Repeated database calls inside loops

What to do

  • Index columns used in WHERE, JOIN, and ORDER BY
  • Avoid SELECT * in production
  • Monitor slow queries early

A fast API is usually backed by a well-designed database.

3️⃣ Error Handling Is Often Incomplete

In dev environments:

  • Errors are visible
  • Logs are easy to read
  • Failures are obvious

In production:

  • Errors may be swallowed
  • Logs may be missing context
  • Failures appear as “timeouts”

What to do

  • Log meaningful errors
  • Return clear HTTP status codes
  • Never hide failures silently

Good error handling makes production issues detectable and fixable.

4️⃣ External Dependencies Are Unpredictable

APIs often depend on:

  • Third-party services
  • Payment gateways
  • External APIs
  • Internal downstream services

In production, these dependencies can be:

  • Slow
  • Temporarily unavailable
  • Rate limited

What to do

  • Use timeouts
  • Add retries carefully
  • Implement circuit breakers
  • Never assume dependencies are always available

Resilience matters more than perfection.

5️⃣ Monitoring Is Added Too Late

Many teams add monitoring after problems appear.

Without visibility:

  • You don’t know where time is spent
  • You don’t know what failed first
  • You react instead of prevent

What to do

  • Track response times
  • Monitor error rates
  • Log important business events
  • Set alerts before users complain

Production systems need eyes and ears.

✅ Key Takeaways

  • Production failures are usually predictable
  • Databases are often the real problem
  • Traffic patterns matter more than code elegance
  • Monitoring and logging are not optional
  • Design APIs for failure, not perfection

If an API works in development, that’s a good start — not the finish line.

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