Vasyl Semiliak, Product Engineer
Warsaw, cet
open to new collaborations
Writing
Your Code on Someone Else’s Page
17 min read
How embeddable widgets like Intercom, Stripe and Calendly load, isolate themselves, talk across frames and ship safely to pages their authors never see.
A Million Files From a Browser Tab
11 min read
A progress bar fix turned into a browser-native upload engine for a million files, with crash recovery, multi-tab coordination, and resumable transfers.
Work
IndependentProduct engineer · B2B
2026–nowI work directly with founders and engineering teams to build and improve their products, and I’m open to new collaborations.
CorelliumFrontend systems engineer
2021–2026Led frontend modernization across a complex enterprise codebase, increasing team throughput, improving code quality, and making it AI-ready.
AgenciesProduct engineer
2017–2021Shipped fintech and healthcare products, from MVPs to complex dashboards and integrations.
AXSYSFounding engineer
2016–2017Built a startup’s first product from scratch, owning technical decisions and delivery.