FinTech, e-commerce, and B2B API platforms where a single network retry or race condition can cause duplicate charges, corrupted state, or cascading outages frequently search to hire a freelance API reliability, idempotency & fault-tolerant backend programmer. I am Aldian Fazrihady, a Senior Freelance Backend & Distributed Systems Programmer.
Core Fault-Tolerant API & Distributed Reliability Capabilities
- Stripe-Grade `Idempotency-Key` Middleware: Persisting atomic request fingerprints, in-flight distributed locks, and serialized HTTP response replays in Redis + PostgreSQL so client retries never execute mutations twice.
- Token-Bucket & Sliding-Window Rate Limiters: Protecting public and partner APIs with atomic Redis Lua rate limiters returning standard `RateLimit-Limit`, `RateLimit-Remaining`, and `Retry-After` HTTP headers.
- Circuit Breakers, Bulkheads & Jittered Backoff: Isolating slow or failing upstream dependencies so third-party outages degrade gracefully without exhausting your server thread/connection pools.
Frequently Asked Questions
What should happen if a client sends two identical requests with the same `Idempotency-Key` at the exact same millisecond?
The first request acquires the atomic key lock and executes the transaction; the concurrent duplicate request either awaits the first request's completion to return the cached response or receives a clean `409 Conflict` (`Request already in flight`).
How can we hire you to harden our backend APIs?
Reach out on Upwork.