--- name: work description: Senior backend engineer from a bank who owns a problem from requirements to production. Use when you are building a system that must not go down. I don't turn a ticket straight into code; first I find out what its author meant. location: Prague, Czechia --- # Josef Dula 10 years in. I helped build a bank from scratch. In a small team we run and develop the card system for hundreds of thousands of cards and all their transactions. In a team of six where I was the only backend engineer, we delivered the first in-bank bitcoin purchase in Czechia. And now I am in the group steering AI across the bank. I ship without downtime, because explaining to people why their card doesn't work is not my idea of fun. What I do enjoy is looking at the data and seeing how many people use what I built. ## When I can help - You are building a system that must not go down or lose data. Not even on a Friday afternoon. - You need someone to take the whole task: clarify the requirements, plan it step by step, get it to production, and not vanish right after the merge - You want AI in production, not in a slide deck - You want someone who brings the team along: helps colleagues and agrees solutions across teams ## Examples **Input:** The bank wanted to be the first in Czechia to let clients buy bitcoin directly in their bank. **Output:** In a team of six I was the only backend engineer. None of us had brought crypto into a bank before, and we work in a heavily regulated environment. The biggest risk was processing a payment twice or losing it on the way, hence the outbox pattern and strict idempotency: when a surrounding service goes down, processing is safely retried, with no duplicated or lost payment. In the first quarter after launch, we didn't have to fix a single bug in our code in production. **Input:** Filling in my timesheet meant trying to remember every day what I'd actually done, and clicking it in by hand. **Output:** Now an agent drafts what I did that day from the available data, and once I approve, it's reported. One sentence and one confirmation. Together with automating the release process, it's one of the things we've been changing in AIVengers since day one. **Input:** Coding agents need a free hand, but must not get the whole developer machine or the company's keys. **Output:** I designed a developer sandbox: the agent works without constant approvals, can only reach pre-approved addresses, and API keys and tokens never enter the sandbox at all; a proxy adds them on the way out. Other teams across the bank are now adopting it. **Input:** Small merchants in the EU needed a simple way to take cashless payments. **Output:** The Trisbee app with a complete Stripe integration: cards, Apple Pay, Google Pay and monthly subscriptions, plus an internal accounting system. ## How I work - A ticket is not a spec, it's the start of a conversation. - I split a big thing into smaller steps that can be shipped safely, with monitoring and data on top, so I know it really works in production. - If it can be deterministic, it should be. An agent should call a tool, not take another guess. - Done means people use it. Until then it's just nice code. - The best solutions come from the team. I like helping the people around me; right now I'm teaching a frontend colleague backend. ## Capabilities - languages: Kotlin, Java, SQL, PL/SQL, TypeScript - backend: Spring, Micronaut, Quarkus, Hibernate, Liquibase, Gradle, PostgreSQL, Oracle, DynamoDB - operations: zero-downtime releases, backward compatibility, idempotency, backup scenarios, observability and monitoring - payments: card issuing and processing, Visa (Click to Pay, Apple Pay), clearing, Stripe - ai: LLM agents, tool calling, MCP, ACP, agent sandboxing, knowledge bases - infra: AWS, Terraform, Docker - delivery: technical specs, staged plans, architecture decisions, team operations ## Changelog ### v3.2 — + AIVengers (Oct 2026 – present) - Added: member of AIVengers, a small group steering AI across the bank ### v3.1 — + Tech Lead Platform (2024 – present) - Added: member of the Tech Lead Platform, which sets the company's technical direction: bank-wide solutions that other teams then adopt. Same role, new features, backward compatible. ### v3.0 — Senior Backend Engineer, Cards @ PBK Technology / Partners Banka (Aug 2023 – present) - Initial: joined before the bank went live — a new bank built from scratch on a modern stack - Added: cards team from day one; a very small team running hundreds of thousands of cards and millions of payments - Added: full Visa integration, including Click to Pay and Apple Pay - Improved: clearing file processing at growing transaction volume - Added: in-bank bitcoin purchase, first in Czechia; the only backend engineer in a team of six, outbox pattern and idempotency ### v2.1 — CTO @ Trisbee (Mar 2023 – Aug 2023) - Changed: a few months as CTO of a small startup — leading a team of about five, production, Jira, AWS costs, password management, technical direction ### v2.0 — Backend Developer @ Trisbee (Jul 2020 – Feb 2023) - Added: payment method for small EU merchants, built in a small international team - Added: core payment components and an internal accounting system - Added: Stripe — cards, Apple Pay, Google Pay, monthly subscriptions - Added: integrations with Mailgun, HubSpot, AWS and Zapier; analytics and reporting ### v1.0 — Integration Developer @ Provys (2016 – 2020) - Initial: PL/SQL integrations between systems (SQL, XML, SOAP, JSON) - Added: migrations of major broadcasters — TV Nova, TVE, BT Sport - Added: team operations — splitting work and estimating capacity - Added: co-built the internal documentation system ### v0.1 — Ing., Information Systems and Technology @ VŠE Prague (2012 – 2018) ## Outside work - **Smart home and automations** — outside work I help people with both. See [smart-home](/smart-home/) and [automation](/automation/). - **Off-duty** — mostly beach volleyball. ## Not a fit - Jobs that are more about meetings and reporting than results. I need to build things and see them work. ## Get in touch Solving similar problems, or building something interesting? Drop me a line. - Email: dulajosef@gmail.com - LinkedIn: [linkedin.com/in/josef-dula-530505b3](https://www.linkedin.com/in/josef-dula-530505b3) - GitHub: [github.com/dulajo](https://github.com/dulajo)