https://rafaelroman.com/articles/ Articles by Rafael Roman on distributed systems, fintech engineering, fraud prevention, energy tech, and engineering leadership from N26, Personio, and Upgrid. en Sat, 10 Oct 2026 10:07:54 GMT https://rafaelroman.com/articles/ai-reverse-engineering-cant-hack-your-bank/ https://rafaelroman.com/articles/ai-reverse-engineering-cant-hack-your-bank/ REA hit GitHub trending and Photoshop clones went viral. Why AI reverse engineering can decompile your banking app but still can't touch the ledger. Sat, 10 Oct 2026 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/building-the-company-brain-at-upgrid/ https://rafaelroman.com/articles/building-the-company-brain-at-upgrid/ How I built Clara, Upgrid's read-only Slack agent over our data, docs and code — and why the hard part was deciding what it could never do. Thu, 08 Oct 2026 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/senior-staff-principal-engineer-ambiguity/ https://rafaelroman.com/articles/senior-staff-principal-engineer-ambiguity/ What separates junior, senior, staff and principal engineers isn't raw skill. It's how much problem and solution ambiguity you can take on, and who finds the problem. Tue, 06 Oct 2026 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/shipping-at-upgrid/ https://rafaelroman.com/articles/shipping-at-upgrid/ Merge to main, live in four minutes. How I ship at Upgrid — 1,400 PRs, a small team, and a cadence that picked up in the last two quarters. Sun, 23 Aug 2026 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/engineering-at-upgrid-tech-stack/ https://rafaelroman.com/articles/engineering-at-upgrid-tech-stack/ Next.js, Supabase, Linear, Steep, PostHog, Better Stack. A tour of the Upgrid stack — how a small team ships Swiss energy billing without a microservice estate. Sat, 22 Aug 2026 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/building-upgrid/ https://rafaelroman.com/articles/building-upgrid/ Co-founding Upgrid as CTO: a Swiss energy-community platform where billing law, metering data, and go-to-market share the same correctness bar as fintech. Fri, 07 Aug 2026 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/rebuilding-fraud-prevention-at-n26/ https://rafaelroman.com/articles/rebuilding-fraud-prevention-at-n26/ How N26 replaced a static rule engine spread across dozens of microservices with a stateful Apache Flink pipeline in six months: new-rule lead time from 4 weeks–6 months to ~2 weeks, payment to decision in ~52ms. Sun, 01 Sep 2024 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/say-yes-first-platform-teams/ https://rafaelroman.com/articles/say-yes-first-platform-teams/ A product engineer brings a small tooling idea to platform. The default response — no, not now, here's why it won't work — builds a wall. There's a better one. Tue, 02 Jul 2024 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/i-hardly-debug-anymore-tdd/ https://rafaelroman.com/articles/i-hardly-debug-anymore-tdd/ I used to relaunch the app five times to check one change. TDD felt like homework until the feedback loop clicked — now tests are how I think, not what I do after. Thu, 16 Feb 2023 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/code-freeze-purpose/ https://rafaelroman.com/articles/code-freeze-purpose/ Code freezes feel like arbitrary bureaucracy — until you're the one on call during the holidays. The real reason companies do them isn't what most engineers think. Tue, 10 Jan 2023 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/engineering-at-n26-tech-stack/ https://rafaelroman.com/articles/engineering-at-n26-tech-stack/ Nine thousand containers, two hundred microservices, one licensed EU bank. An insider tour of how N26's stack actually worked — and the parts we hadn't finished yet. Thu, 29 Sep 2022 00:00:00 GMT Rafael Roman https://rafaelroman.com/articles/straight-out-of-the-bootcamp/ https://rafaelroman.com/articles/straight-out-of-the-bootcamp/ You finished the program. Now what? Stop collecting certificates. Build something recruiters can click. Prepare like interviews are the job — because for a while, they are. Mon, 06 Sep 2021 00:00:00 GMT Rafael Roman