Open to opportunities

Jan Lis

@janlis

Message

I build reliable, well-tested Python backend systems with pragmatic, maintainable architecture.

Poland

Message

What I'm looking for

I'm looking to build reliable, readable, well-tested systems where I can understand the business context and make pragmatic technical decisions.

I've owned document-processing services at Intive GmbH, redesigning email and file-processing pipelines to halve processing time and reduce infrastructure costs by 90%.

I build backend features, internal tooling, and REST APIs using Python, Django, DRF, Flask, PostgreSQL, and Solr. I also handle production issues and support requests while keeping systems reliable, readable, and well-tested.

At 360CodeLab, I contributed to product and implementation decisions, mentored two junior backend developers, and participated in technical recruitment interviews. At Predict Systems, I built backend features, dashboards, and internal reporting tools while collaborating with data science on A/B testing and analytics support.

As a freelancer since 2015, I've delivered 20+ commercial projects end-to-end, including an industrial lighting control system for Gdańsk Shipyard integrated with DALI controllers. I care about understanding business context, clean abstractions, and pragmatic solutions free from unnecessary complexity.

Experience

Work history, roles, and key accomplishments

Current

Freelancer

Current

Self Employed

Jan 2015 - Present (11 years 7 months)

Delivered 20+ commercial projects end-to-end. Built and launched an industrial lighting control system for Gdańsk Shipyard, integrating with DALI controllers.

Senior Software Engineer

Intive GmbH

Feb 2023 - Jul 2026 (3 years 5 months)

Owned document processing services; redesigned and implemented new email and file-processing pipelines; processing time halved, infrastructure costs 90% down. Refactored backend features, built internal tooling and handled production issues and support requests.

Python DRF Solr PostgreSQL Claude Code

Senior Backend Developer

360CodeLab

Oct 2021 - Nov 2022 (1 year 1 month)

Built REST APIs, contributing to product and implementation decisions. Mentored two junior backend developers and participated in technical recruitment interviews.

Python DRF Flask MS SQL Server

Backend Engineer

Predict Systems (P42)

Jun 2020 - Sep 2021 (1 year 3 months)

Built backend features, dashboards and internal reporting tools in a dynamic research-oriented product. Collaborated closely with the data science team on A/B testing and analytics support.

Python Pandas DRF PHP