Jan Šťastka
Full Stack Developer
Software Integration Specialist
Software Engineer at R2B2 · Full Stack Developer focused on React architecture, ad tech infrastructure, and frontend performance.
About Me
A bit of context
I am a Full Stack Developer and Software Integration Specialist focused on frontend performance, React architecture, and ad tech infrastructure. Currently at R2B2 as a Software Engineer, I own React components and E2E tests, support custom web apps for AYM & Caroda, and drive platform merges. Previously at Avon for 3+ years, I built and published web platforms across CZ/SK markets, redesigned homepages, relaunched the customer club with Svelte, and automated export pipelines that cut a 2-day process down to 1 hour.
Work Experience
Where I've been and what I've built
Software Engineer
R2B2 Ad monetization partnerResponsibilities: Custom web app support (AYM & Caroda) · Ensuring ad script delivery and quality · Main owner of React components & E2E tests · Collaboration on platforms merge (R2B2 & Caroda).
Achievements: Finished ongoing redesign · Rework from React Table to TanStack Table · Replace drag & drop and date picker libraries · Upgrade React from v16 to v18 & prepare for v19 · Migration from Timescale to ClickHouse · Reduce ad delivery script size by ~10% gzip (~30% raw) · Automate ad placement creation in Caroda.
Web Publisher
AvonResponsibilities: Content controller of platforms (MAS CZ/SK) · Web publisher and frontend developer of MAS CZ/SK · Web optimization · Overseeing Content & Campaign setup for avon.cz, avon.sk · Creation of web pages.
Achievements: Built components for Avon's platforms (address validation, product carousel, promo code section) using HTML, CSS, JS, GTM, Dynamic Yield · Menu & small components on avon.cz · Anew product page · Valentyne's product page · Christmas gift finder.
Key Tester & Content Controller & Incidents Manager
AvonResponsibilities: Content controller of platforms (MAB CZ, GI3 SK, NOEL CZ/SK, MAO CZ/SK) · UAT testing across avon.cz, avon.sk, AvonON app, Grow app, Digital brochure, Avon Rewards, Loyalty Club · Incidents management & PROD Smoke/Sanity tests · Participation in Digital Projects (MAB, GI3, MAO Avon Rewards, Grow web).
Achievements: Homepage redesign for avon.cz & avon.sk using HTML, CSS, JS · Customer club relaunch using Svelte · Innovation of processes — CSV export from 2 days to 1 hour, semi-automated product validation between platforms, user-friendly NOEL exports (JSON).
Skills & Technologies
What I work with
Core Stack
Frontend
Backend & Data
Testing & Quality
Tools & Platforms
Languages
Communication across borders
Get in Touch
Let's build something together
Whether you have a project in mind or just want to say hi — my inbox is always open.