.NET Backend Engineering
I have worked with C#, Entity Framework, and .NET from the early 1.0 days through modern .NET 8 applications.
$ whoami
Bartosz Siekański
Software developer based around Katowice, Poland. I build practical web systems, cloud infrastructure, readable backend code, and frontend apps that feel fast enough to disappear.
About Bartosz
$ cat about.txtBartosz Siekanski, also written Bartosz Siekański, is a software developer in the Katowice area in Poland. This portfolio highlights his software engineering work, C# and .NET experience, Entity Framework, AWS infrastructure design, React, React Native, Next.js, Vue.js, jQuery, vanilla JavaScript, Goddit experience, senior backend developer and tech lead work at Northmill Bank, and technical interests in local LLM models, AI code-first development, agentic AI, Linux, shell workflows, Git, APIs, and maintainable systems.
Tech Lead Experience
I worked as a tech lead and senior backend developer at Northmill Bank, a Swedish bank, leading delivery on backend systems.
Full-Stack Product Work
I have built apps with React, React Native, Next.js, Vue.js, jQuery, and vanilla JavaScript across different product needs.
AWS Infrastructure
I have used many AWS resources and designed infrastructure for systems that need to be reliable, observable, and maintainable.
Selected Work
$ ls ./work
01
Goddit Software Development
Current professional home for product work, engineering decisions, and day-to-day software delivery.
visit 02Northmill Bank
Tech lead and senior backend developer experience in Swedish banking systems.
visit 03Bartosz Siekański LinkedIn Profile
Public profile with experience, connections, education, and current career details.
linkedinTechnical Stack
$ printenv SKILLSSoftware Development Tools
A compact toolkit for building, debugging, deploying, and maintaining software without ceremony.
Now
$ tail -f experiments.logLocal LLM Models
I am experimenting with local language models, private inference, and developer workflows that can run close to the code.
AI Code-First
I am exploring an AI code-first approach where specifications, review loops, tests, and implementation evolve together.
Agentic AI
I am testing agentic AI patterns for software delivery, automation, investigation, and repeatable engineering tasks.