End-User Notification Platform: built platform delivering 1M+ notifications/day to mobile and email.
Distributed Compute Infrastructure: rebuilt single-node query engine for multi-node parallelism, SME for Apache Ignite.
Fraud Detection System: full rewrite for 50x speedup (weeks to hours), mandatory feature for $68M ACV in deals.
Data Collection Systems: operated 1M+ LoC codebase with 100k+ visitors/day, defense against DDoS/spikes/probes.
