Independent Software Engineer— Freelance02/2025 – Present
Designed and shipped Ksefiliusz, a cross-platform desktop application for Poland's national KSeF e-invoicing system. Created and maintain several open-source projects and take on freelance work for multiple clients. Deepened expertise in systems programming and computer science fundamentals, with a focus on C, Rust, Assembly, computer architecture, networking, and cybersecurity.
Backend Developer— Lerta (currently Photon Energy)10/2022 – 02/2025
Developed and maintained a distributed backend of ~150 microservices across Go, Java, Python, and TypeScript for an IoT platform supervising PV farms, wind turbines, and biogas plants, plus an energy trading system and customer/admin web applications. Designed and optimized time-series pipelines in TimescaleDB and InfluxDB processing billions of records, resolved Kafka and RabbitMQ bottlenecks, and managed Kubernetes deployments with Helm, Docker, and CI/CD. Provided on-call support and ran technical interviews on Go and system design.
Software Engineer— Amartus10/2021 – 10/2022
Built backend and full-stack services to provision and monitor F5 BIG-IP devices, covering DNS, L4/L7 load balancing, and firewall configuration over their device APIs. Worked close to the network layer and provisioned Linux VMs on Type 1 and Type 2 hypervisors for device emulation. Collaborated daily with network engineers across the UK, China, and India.
Backend Developer— Dev an Deliver03/2020 – 12/2021
Built REST and GraphQL APIs in NestJS, integrating Salesforce, Stripe, and HubSpot for a mobile service-ordering app and an interactive educational platform. Implemented asynchronous messaging pipelines with RabbitMQ with high availability in mind, managed cloud infrastructure on Azure and DigitalOcean using Docker and Kubernetes, and mentored new team members through code reviews and pair programming.
