Grzegorz Śliwiński — CV

Grzegorz Śliwiński

Principal Python Software Engineer and Project Tech Lead, 13 years in AdTech. Leads technical direction, designs scalable Python/Go systems, and improves the processes around them. Favours incremental, adoption-led change over rewrites, backed by the tooling and documentation that make it stick.

Email:

fizyk@fizyk.dev

Citizenship:

Polish

Languages:

Polish (Native), English (Fluent / Professional Working Proficiency)

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Skills

  • Python, Go

  • FastAPI, Django, Django Rest Framework, fasthttp, Flask, SQLAlchemy, Alembic, Pytest (including plugin development), Pyramid

  • AWS (Glue, Lambda), GCP (BigQuery)

  • AWS Redshift, PostgreSQL, DynamoDB, Redis

  • Docker, Docker-compose, Terraform

  • Azure Pipelines, Bitbucket Pipelines, GitHub Actions

  • MCP servers, memory and performance profiling

  • mise/asdf, pre-commit/prek

Experience

Principal Python Software Engineer at Spyrosoft

2026.01–Present

  • Two projects for one AdTech client. Established the codebase's Architecture Decision Records practice, using Nygard's template, and brought the team onto automated dev tooling version management (mise/asdf) with pre-commit hooks (prek).

  • Delivered features through AI-assisted development, using Claude to refine, plan and implement, with self-review and team code review kept as gates.

Campaign planning support tool

2026.05–Present

  • Productionised an internal experiment into a running service, implementing its API and MCP server.

  • Cut the service's memory footprint to its FastAPI runtime baseline after introducing memory profiling.

Campaign management platform

2026.01–2026.05

  • Took over the reporting component as the colleagues holding it were moved to another project, ironing out implementation details through the handover.

  • Inherited a reporting feature the previous team had built in its final week and halved its BigQuery cost.

Staff Python Engineer at Avenga

2025.09–2025.12

  • Engineer on a Go-based bidder built on Fiber (fasthttp), on GCP with BigQuery.

  • Restored code quality tooling the team had abandoned, and the tool-version pinning it needed to stay consistent across developers.

  • Identified maintainability and auditability risks in a SQL-query-based targeting implementation and proposed an alternative direction for it.

  • Introduced the same ADR practice to the bidder codebase.

Project Tech Lead at Clearcode / Avenga

2023.01–2025.08

Also operating as Staff Python Engineer, 2025.01–2025.08

  • Took technical leadership of the video ad-server in 2023, after more than a year on it as an engineer, and saw the four-year project through to its close — scoped to the project rather than a team, once the acquisition had dissolved Clearcode's team structure.

  • Clearcode merged into Avenga in January 2025.

  • Led the technical direction of AdTech systems in Go and Python.

  • Worked with Product Owners on requirements, and split them into tasks.

  • Cut quarterly planning from a full week to under an hour by keeping alignment with the Product Owner continuous rather than quarterly.

  • Rewrote the documentation so clients and the team could find what they needed.

Senior Engineer at Clearcode

2021.10–2022.12

  • Stepped back from team leadership by choice to build the video ad-server as an engineer, having designed it that June.

  • Built and maintained scalable AdTech systems in Go and Python.

  • Worked directly with clients on functional and non-functional requirements.

Team Tech Lead at Clearcode

2017.01–2021.10

  • Ran the team's technical work, from system design through the delivery lifecycle.

  • Handled shifting client requirements as projects moved.

  • Turned requirements into tasks and planned how they landed.

Project Manager at Clearcode

2016.01–2016.12

  • Took the role over on the outgoing PM's recommendation.

  • Rebuilt team morale and defused a strained client relationship.

  • Reworked the team's workflow.

  • Managed a team of up to 17 people.

Python Developer at Clearcode

2013.06–2015.12

  • Built and maintained real-time bidding DSP platforms.

  • Took the core product from proof of concept to production, architecture and monitoring included.

  • Held ad impression reporting to a 2% discrepancy, against a 10% industry norm.

Python Developer at Red Sky sp. z o.o.

2010.10–2013.05

PHP Programmer at Webstyle Systems

2010.03–2010.07

Education

Master of Science in Software Engineering

Wrocław University of Science and Technology, 2007–2010

Engineer, Information Technology Faculty, Computer Systems and Networks

University of Information Technology and Management "Copernicus", 2003–2007

Certifications

AWS Certified Solutions Architect – Associate

2019–2022, Credential ID: AWS00961561