Backend Engineering

Practical insights on APIs, databases, performance tuning, and the craft of building reliable server-side systems.

2 posts in Backend Engineering

Idempotency: Why POST Should Sometimes Act Like PUT

The client's network dropped right after they hit 'Pay.' Did the charge go through? They retry. Now you might charge them twice. Idempotency keys are how you let clients retry safely without double-processing — and they're more subtle than they look.

idempotencyAPI designRESTretries

Jun 4, 2026Read

Backend Engineering|7 min read

Database Indexing — How It Actually Works Under the Hood

Most developers know indexes make queries fast. Few understand why. This post breaks down B-Tree indexing, query planning, and the exact mechanics that turn a 2-second query into a 2ms one.

databaseindexingB-TreePostgreSQL

Feb 5, 2026Read