Software Developer at SurveySparrow, two years on the billing and payments platform. I build the systems that decide whether a company gets paid correctly.
Two years inside a live billing platform. Millions of subscriptions across seven datacenters, and one rule: the money and the data must always agree. When they drift, I find out why, fix the root cause, and build the guard that stops it coming back.
The product kept its own copy of billing state, synced by webhooks. Every missed event became a wrong plan, a wrong limit, a wrong invoice. I architected the decoupling of billing into SparrowPay and re-pointed 230 read paths across 65 files to the one system that knows the truth.
Led a cross-system subscription audit across 2 datacenters. Grouped every mismatch into 7 root causes and drove 6 targeted fixes. Then turned the audit into a daily reconciliation job that has since surfaced 400 mismatches before any customer noticed.
Concurrent events for the same account deadlocked each other, and any payload field could write straight into billing. I added per-account Redis locks so one account serialises while millions run in parallel, plus a strict 30-field allowlist across 25 event types.
Provisioning features for every account ran row by row and took two days, so plan launches waited on it. Batched inserts and 20 parallel workers with bounded concurrency, safe to re-run midway. Plan rollouts stopped being a weekend job.
An audit cron for superadmin overrides protects about $50K a year from quietly leaking. A Slack bot watches payment attempts for stolen cards and has flagged 10+ fraud attempts in real time. A pause-payment workflow keeps Stripe and internal billing at 100% consistency through suspensions.
Every billing bug I have fixed followed the same arc. The difference between a patch and an engineer is whether the arc finishes.
Compare what the product believes with what billing knows, across every datacenter. 190 accounts were wrong before anyone could say how many.
Not the symptom. Seven causes behind 190 mismatches became six fixes. A second copy of billing state became no copy at all.
A daily reconciliation job, per-account locks, an override audit cron, a fraud bot. Guards that run while everyone sleeps.
48 hours to 4. $50K a year. 100% consistency. If it cannot be measured, it is not finished.
WorkQueue, a distributed job-queue library in Java 21 on Redis: at-least-once delivery, strict per-key ordering, retries with backoff, dead letters. 1,900 ops/sec under a 10,000-item load, zero messages lost in crash tests. Education: B.Tech Information Technology, Sona College of Technology, 2021 – 2025, GPA 8.0.