High-throughput engine — 10+ order and card transactions a second, 250K a day, with Redis as the primary database. Handles complex system roundtrips and human-in-the-loop workflows without slowing down.

Platform leadership — leads the payments platform team across acquiring, terminals, and allied services. Owns technical direction and delivery — and still ships core transaction flows hands-on.

AI agent factory — builds agent systems that write production code, wired into the team's repositories. Faster shipping, higher code quality.

Authentication Gateway — event-driven NodeJS / Postgres / Redis service integrating multiple payment acquirers with millisecond-latency authentication. Proven under extreme load: $30M+ across 100K+ transactions during New Year's celebrations, without incident.

Terminal Management System — architected and built the entire system: software distribution, complex EMV configuration, and a custom protocol speaking to 2,000+ terminals. Eliminated manual fleet operations — a structural advantage over competing terminal providers.

Payment SDK (Kotlin) — the SDK behind the payment app on 500+ terminals, managing card payments and backend communication for 10K+ payments a day with low latency.

WebSocket servers — centralized connection management with in-house pub-sub for 1,000+ terminals: 60% cut in resource usage, 40% latency improvement through asynchronous design. Plus feature work and debugging in C on bare-metal payment hardware.

Gateway optimization — revamped the application that routes all inbound and outbound API traffic to the right microservices. Designed a lean multi-layer data structure that eliminated runtime decisions — 40% increase in traffic handling capacity.

Payments Service — multiple payment methods (card, Swish) handling 100K+ daily transactions with ACID guarantees, on NodeJS / Postgres / Redis.

Tokenization System — implemented and maintained a PCI-certified tokenization system on GCP HSM: tokenizing, encrypting, and securely storing card details — then leveraged for loyalty programs and POS customization.

Also shipped: the device-management Android client (Kotlin), a custom command-subscription pattern (CSRS) over Redis, control-unit and product-catalogue services.

Designed and implemented a compiler for a programming language of my own design. Collaborated with a cross-functional team of mobile and web engineers to design and build a backend API for online bike sellers on NodeJS and Firebase.

Multi-tenant core — TypeScript / Bun backend on PostgreSQL with row-level security isolating every merchant, 600+ passing tests, real-time kitchen order flow over MQTT, analytics on ClickHouse.

Offline-first clients — Flutter POS and kitchen kanban that keep taking orders when the network drops (local-first storage, sync on reconnect), a QR self-ordering menu, a Next.js merchant dashboard, and thermal-printer integration.

Finance engine — double-entry bookkeeping built for restaurants: OCR expense capture from email ingest, GST handling, and automated multi-way bank reconciliation.

AI-operable — an MCP server that lets an LLM run the whole POS in natural language: place orders, pull analytics, take payments.

ISO 8583 — contributed hex encoding for variable-length fields and field-127 extensions to an open-source ISO 8583 messaging library — the format card networks actually speak.

TLV workbench — a UI toolkit for dissecting TLV (Tag-Length-Value) strings, the encoding inside EMV chip transactions.

Systems for sport — a Redis RESP protocol mock, a Redis Streams client library, and a database engine built in a 16-hour hackathon and deployed to Cloud Run.