At Varo Bank I owned backend systems touching 2M+ customers and $100M+ in monthly transaction volume. I built the identity resolution system from scratch cutting manual reconciliation by 40%, migrated ACH processing to an async Kafka pipeline dropping transaction time from 4.2s to 380ms, and brought auth-related production incidents from 12 per month to zero via OAuth 2.0. I treated every system I touched as if I owned it in production — because I did.

At Walmart Global Tech I built Cart and Checkout systems serving hundreds of millions of users. I parallelized inventory calls dropping p99 latency from 780ms to 118ms, applied Cassandra optimistic locking across 50K+ daily concurrent cart merges, and authored compensating transactions in our checkout saga eliminating 15–20 weekly manual interventions. Our Kubernetes HPA configuration on GCP GKE sustained a 3x Black Friday traffic surge with zero degradation — building systems where failure was not an option.