Open to opportunities

Kostiantyn Polishchuk

@kostiantynpolishchuk

Message

I build reliable LLM applications with RAG, retrieval, agentic workflows, and production-grade evaluation.

Poland

Message

What I'm looking for

I'm looking to build reliable LLM applications end-to-end, spanning solution design, retrieval architecture, APIs, evaluation, testing, observability, and deployment. I'm open to relocation.

I've built and deployed a multilingual RAG system for natural-language search across approximately 113K Steam games, using hybrid retrieval, Qdrant, BM25, dense embeddings, metadata filtering, and structured LLM query understanding. I design AI systems end-to-end, from retrieval architecture and APIs to evaluation, testing, observability, and deployment.

I also built an AI web auditor combining deterministic rule-based checks with a bounded LangGraph agent workflow, including validation, fallbacks, automated tests, and CI. Earlier, at InkBook Europe, I developed and maintained production Android e-reader software in Kotlin and Java.

Experience

Work history, roles, and key accomplishments

Android Developer

InkBook Europe

Jan 2022 - Jun 2022 (5 months)

Developed and maintained production Android e-reader software in Kotlin and Java, working with UI components, APIs, and existing application architecture. Investigated complex application issues using Android Studio, ADB, Logcat, stack traces, and systematic root-cause analysis.