Where I work, what I own, and what I build to understand the layer underneath.
I am Mahir Jain, a Backend Engineer in Go. I work on distributed systems where a bug becomes someone's bill: EV charging, tenant isolation, and event-driven transactions. Currently one of two engineers on a five-module OCPP/OCPI platform, where I own the charging-session and billing-integrity path. Outside client work I build databases and infrastructure from scratch to understand how they actually behave. I also work daily with Claude Code, Codex, and agent orchestration, and I review everything they produce before it lands.
Highlights
Production OCPP 1.6 / 2.0.1 and OCPI 2.2.1 backends in Go
Fixed a cross-user billing defect and a 1000x unit misread, both with deterministic regression tests
One WebSocket endpoint serving two protocol versions and two auth profiles through one domain model
Multi-tenant SaaS on MongoDB with database-per-tenant isolation and Saga coordination
B+ tree SQL engine in Go: WAL-backed ACID, MVCC, LRU buffer pool
Caching reverse proxy implementing RFC 7234 with request coalescing
