(Jul 2020 - Sep 2026)
Senior Full-Stack & AI Software Engineer
G2A.COM
Spent several years helping G2A run a marketplace used by millions of people — the everyday buying and selling experience, and later the AI work sitting behind it.
View Details
constcoder={name:'Greg Bak',skills:['React', 'TypeScript', 'Next.js', 'Java', 'Spring Boot', '.NET', 'Node.js', 'PostgreSQL', 'AWS', 'RAG', 'LLM APIs'],hardWorker:true,quickLearner:true,problemSolver:true,hireable:function() {return(this.hardWorker&&this.problemSolver&&this.skills.length>=5);};};ABOUT ME
Who I am?
My name is Greg Bak. I am a Senior Software Engineer based in Kraków, Poland, with 15+ years of experience building full-stack applications, backend services, and cloud platforms across digital commerce, media, healthcare, and business software. My core stack includes React, TypeScript, Next.js, Java, Spring Boot, REST APIs, SQL, and AWS, with additional experience in Node.js, PHP, .NET, and Microsoft Azure. Recently I have focused on AI application engineering — LLM integration, prompt engineering, retrieval-augmented generation (RAG), embeddings, semantic search, and workflow automation. I care about maintainable architecture, reliable delivery, and software that holds up in production.
GB
GREG BAK
Senior Software Engineer
Kraków, Poland
Experiences
stack.tsx
import { React, TypeScript } from 'frontend'
import { Java, SpringBoot, DotNet } from 'backend'
import { AWS, Azure, Docker } from 'cloud'
const delivery = 'RAG · LLM · PostgreSQL'
React
TypeScript
Next.js
Java
.NET
PostgreSQL
AWS
Docker
Azure
Git
PHP
Angular(Nov 2018 - Nov 2019)
Full-Stack Software Engineer
Schibsted Tech Polska
Built advertising tools for Nordic news brands — the kind of work that sits behind the ads readers see on Aftonbladet, VG, and Aftenposten.
View Details(Feb 2018 - Jul 2018)
Full-Stack Software Engineer
rspective
A focused stretch on a Swiss practice platform for therapists. I picked up a major feature and walked it all the way to something people could use in clinic.
View Details(Oct 2017 - Dec 2017)
Frontend Software Engineer
Grand Parade
A short, intense stint at William Hill's Kraków hub, making casino game landing pages feel livelier and easier to play with.
View Details(Nov 2013 - Jul 2016)
Backend Software Engineer
AppDate
A few years on a live-event product — order from your seat, tills, stock, reports. I spent most of my time on the engine that kept all of that talking to each other.
View Details(2009 - Jul 2016)
Full-Stack Software Engineer
Freelance / Contract Projects
Alongside full-time roles I built complete sites for independent clients — the kind of work where you are the whole team, from first conversation to launch.
View Details(Mar 2011 - May 2013)
Full-Stack Software Engineer
Dignitally
Websites and Facebook apps for a Kraków agency — often starting from a blank page and turning a design into something a brand could run a campaign on.
View Details(Mar 2011 - Dec 2011)
Full-Stack Software Engineer
Premium Consulting | IT Outsourcing & Offshoring
Client sites and Facebook applications for Polish companies, turning briefs and designs into working products.
View DetailsSkills
Educations
2008 - 2012
MSc, Computer Science
Cracow University of Technology
2007
Degree Programme in Software Engineering
Jyväskylä University of Applied Sciences
2004 - 2008
BSc, Computer Science
Cracow University of Technology
Certifications
Projects
G2A Digital Marketplace
www.g2a.com
Senior Full-Stack & AI Engineer
The world's largest marketplace for digital entertainment, connecting millions of buyers with verified business sellers across game keys, software, gift cards, and subscriptions. Contributed full-stack marketplace capabilities spanning catalog, checkout, account, and transaction workflows using React, TypeScript, Java/Spring Boot, and PostgreSQL.
ReactTypeScriptNext.jsJava
View projectG2A Plus Membership
www.g2a.com/plus
Senior Full-Stack Engineer
Subscription membership for G2A shoppers offering member pricing, Plus Points, monthly rewards, and priority support. Worked on frontend flows, REST integrations, and backend services that connect membership state with checkout and account experiences.
ReactTypeScriptNext.jsREST APIs
View projectG2A Goldmine Affiliates
www.g2a.com/goldmine
Senior Full-Stack Engineer
Referral and affiliate program that lets partners earn commission on marketplace purchases and G2A Plus memberships. Built and maintained dashboard-oriented interfaces, tracking workflows, and service integrations for partner performance and payouts.
ReactTypeScriptJavaSpring Boot
View projectG2A Seller Dashboard
www.g2a.co/marketplace
Senior Full-Stack Engineer
Seller operations portal for verified business merchants — offer creation, stock and key management, pricing, verification, and sales reporting. Developed scalable APIs and React interfaces supporting high-volume digital-goods operations.
ReactTypeScriptJavaSpring Boot
View projectG2A B2B Marketplace
www.g2a.co
Senior Full-Stack Engineer
Business-facing marketplace channel with AML-verified sellers, CPS commercial model, and seller APIs for catalog import, pricing, and offer automation. Contributed service integrations, validation, and resilient data exchange across marketplace components.
ReactTypeScriptJavaSpring Boot
View projectG2A AI Content Intelligence
www.g2a.co/marketplace
Senior AI Software Engineer
LLM-powered application workflows for content processing, structured information extraction, and AI-assisted operations. Designed prompt-engineering strategies, output validation, and REST integration of model responses with backend data-processing services.
ReactTypeScriptLLM APIsPrompt Engineering
View projectCONTACT
Contact with me
If you have any questions or concerns, please don't hesitate to contact me. I am open to senior engineering and AI application roles that align with my skills and experience.