Software Technical Lead & Distributed Systems Architect / Defacto Technology

Jul 2023 – Current

• Offline-First & Resilience: Architected a mission-critical Offline-First POS & Store Application handling high-volume transactions across ~500 stores and ~2,000 registers nationwide, which keeps operating without the central systems during WAN, MPLS or central DHCP failures.
• Microservices & P2P Architecture: Oversee the system design and operation of 22+ distributed microservices (.NET / Go), implementing gRPC-based P2P messaging and local fallback caching (SQLite/LiteDB) with eventual consistency.
• Low-Level Network Engineering: Built custom Win32/C# API integrations (P/Invoke) for dynamic L2 subnet discovery (10.x.x.x), resolving local POS/device mapping instantly without relying on central network infrastructure.
• Team Leadership & Technical Governance: Lead a team of 6 senior/expert engineers, drive R&D initiatives (Rust/systems programming, Kubernetes pod scheduling policies) and mentor the team on resilient system patterns.
• Self-Checkout: Building Self-Checkout kiosks on the same offline-first foundation, with a redesigned, intuitive B2C UI that stays fully operational during network disruptions.

Senior Developer / Defacto Technology

Apr 2021 – Jun 2023

• Developed backend and frontend of mobile and web cash register applications; delivered new features, performance optimizations and code quality through reviews and best practices.
• Integrated physical Worldline (formerly Ingenico) POS terminals via the IMPPro ECR protocol, letting cashiers start a payment in the app and complete it on the device.
• Took part in architectural decisions. Stack: .NET 6/7/8, Go, SQL Server, Couchbase, Elasticsearch, Flutter, Vue.js, Dapr, NATS.

.NET & Web Developer / 0ve1 I.T.

Dec 2015 – Mar 2021

• Developed backend and frontend of tourism and booking web projects, including booking forms and third-party API integrations.
• Implemented service-oriented architecture with ASP.NET Web Forms and WCF; maintained legacy systems.
• Built responsive, cross-browser interfaces with jQuery and Bootstrap.

.NET & Web Developer and Server Administrator / YS Group

Aug 2014 – Jun 2015

• Led development of ad and e-commerce systems; built scalable web applications with ASP.NET MVC and Entity Framework.
• Implemented dynamic user interfaces with Angular.js, jQuery and Bootstrap.
• Managed Windows Server environments (IIS, DNS), deployment automation and system monitoring.

Surviving Central Infrastructure Failures with Offline-First POS Architecture

Offline-First · Edge Computing · Fault Tolerance · Retail

An architectural walkthrough of how a nationwide retail POS system (~500 stores, ~2,000 registers) was redesigned to keep stores operating through WAN, MPLS and central DHCP outages: local state management, SQLite edge storage, decoupling business logic from the data source, NATS JetStream synchronization and eventual consistency.

High-Throughput Store Synchronization Using gRPC & Local Eventual Consistency

gRPC · P2P Messaging · Distributed Systems · Synchronization

A deep-dive into the P2P synchronization layer built between store registers: protocol design, conflict resolution, LiteDB/SQLite delta propagation, and the trade-offs of applying eventual consistency in a high-throughput, low-latency retail edge environment.