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Staff Software Engineer · Kotlin, Spring Boot, Kafka · openapi-generator contributor
I turn messy backend domains into systems a team can run and change.
Open to Staff+ backend roles in Israel, on-site or hybrid.
Discuss Staff+ backend work me@yonatankarp.com
I work where product rules, vendor integrations, event flows, and operational risk meet.
Every floor is a chapter of my CV. ScrollSwipe to go inside, or pick a window.
Latest post: I Stopped Being My AI Agent's Memory · Podcast: The Reading Club · Garage: projects ↓
My strongest fit is Staff+ backend work where the domain has to become one system the whole team understands.
RoofWriting, podcast, contact
If your backend domain needs untangling, let's talk.
My strongest fit is Staff+ backend work where the domain has to become one system the whole team understands.
People use the same words for the system and rely less on folklore. Tradeoffs are written down where the team can find and challenge them later. A problem that keeps coming back becomes an example, a library or a template anyone can pick up, and the system gets easier to change because more people know why it works the way it does.
An AI-generated podcast of concise summaries of software engineering books. The Reading Club on Spotify
Case study · Compliance platform Creating a new service boundary for compliance workflows.
Case study · Engineering leverage Turning repeated operational friction into shared tooling.
Responsible for the reliability of the payments and compliance platform: service boundaries, vendor integrations, migrations, and operational tooling.
Billie, Berlin, GermanyOct 2025 – Present
Staff Software Engineer, Payments
Responsible for the reliability of the payments and compliance platform: service boundaries, vendor integrations, migrations, and operational tooling.
Compliance platform
Context
Transaction monitoring, screening, and sanction checks crossed product rules, vendor behavior, alerts, and audit expectations.
Decision
I authored the technical spec and interfaces, led the transaction monitoring vendor integration, and covered Kafka DLT alerts, settlement reports, and compliance states in the service design.
Result
Operational knowledge that was scattered now sits in one service teams can monitor and recover.
Engineering leverage
Context
Platform work gets expensive when incidents, cronjobs, migrations, and service setup depend on private memory.
Decision
I build Backstage tools, templates, migration plans, and upstream fixes when the reusable path beats another one-off patch.
Result
Engineers start from a known path and can challenge decisions through specs, dashboards, examples, and code.
Case study · Risk architecture Moving risk work toward explicit orchestration and contracts.
Led Staff-level risk work: moving risk decisions from Purchases into a dedicated orchestrator, the graph fraud integration, and the target architecture for buyer risk.
Billie, Berlin, GermanyApr 2025 – Oct 2025
Staff Software Engineer, Risk
Led Staff-level risk work: moving risk decisions from Purchases into a dedicated orchestrator, the graph fraud integration, and the target architecture for buyer risk.
Risk architecture
Context
Risk decisions depended on multiple services, fraud providers, recurrent identification, tokenization, and direct debit behavior.
Decision
I co-designed the Risk Orchestrator, led the fraud vendor integration, and authored the Buyer Risk Assessment target architecture.
Result
Coordinating a risk change across providers, payment behavior, and service boundaries got clearer.
Built Risk's credit limit and fraud-labelling services, and moved risk signals to event-driven, engineering-owned pipelines.
Billie, Berlin, GermanyNov 2023 – Apr 2025
Senior Software Engineer, Risk
Built Risk's credit limit and fraud-labelling services, and moved risk signals to event-driven, engineering-owned pipelines.
Built shared backend foundations: a service template, a money library used across backend and Android, and large data migrations.
SumUp, Berlin, GermanyJun 2019 – Nov 2023
Senior Software Engineer
Built shared backend foundations: a service template, a money library used across backend and Android, and large data migrations.
Backend development on a distributed product, focused on cache performance and reliability.
Vision-processing algorithms in C++, and production lines for the chips in South Korea and China.
Courses, degrees, and topics that keep showing up in the work.
Courses and workshops:
Reichman University2012 – 2016
B.Sc. Computer Science
Courses, degrees, and topics that keep showing up in the work.
He sets the bar for what a Staff Engineer should beMohamed Bouallegue, VP of Engineering at BillieLinkedIn recommendation, Oct 2026
I'd love to work with Yonatan againBlake Irvin, Leading Observability Engineering at SumUpLinkedIn recommendation, Sep 2025
the go-to person for almost any problemOren Hadri, Former Engineering Manager at InuitiveLinkedIn recommendation, Oct 2018
a highly talented and disciplined software developerShimon Schocken, Computer Science Professor, Reichman UniversityLinkedIn recommendation, Oct 2018
Down to the garage: projects ↓
Latest writing: I Stopped Being My AI Agent's Memory · All posts
LobbyHow I work
In backend work the hard part is usually finding the real boundary: whose rule it is, which event is authoritative, what happens when a vendor disagrees, and how the next engineer will debug the failure at 2 a.m.
That is usually where I help. I keep asking until the domain is crisp enough to model, then turn it into production code, API contracts, migration plans, dashboards, runbooks, or diagrams that survive the handoff.
Good code is part of it. Most of the payoff comes later, when the whole team can run the system, extend it, and argue about it with evidence.
I’ve worked with many strong engineers, but very few like Yonatan.
What sets Yonatan apart is that he thinks like an engineer and a business owner at once. He brings strong technical judgment, but he’s driven just as much by understanding what the business actually needs. That combination made him a multiplier at Billie: he shipped high-quality systems, and he found opportunities that other teams went on to build on.
Yonatan was the person we turned to when priorities changed. When we moved him to a new domain, he took full ownership almost immediately and delivered as if he had been there from the start. That level of adaptability is rare, and it gave us real flexibility as an organization.
He is also always looking ahead. He was a driving force behind AI adoption at Billie, and his work fundamentally changed how we build software. He made it part of how we work instead of a side experiment.
He sets the bar for what a Staff Engineer should be. Any organization that gets to work with him is lucky, and I’d jump at the chance to work with him again.
Mohamed Bouallegue, VP of Engineering at BillieLinkedIn recommendation, Oct 2026
I’d love to work with Yonatan again. He’s incredibly smart, cares deeply about quality but balances this with delivery speed, and (maybe most importantly) a great human to be teammates with.
Blake Irvin, Leading Observability Engineering at SumUpLinkedIn recommendation, Sep 2025
I was privileged to have Yonatan on my team for almost 3 years. Yonatan is a dedicated, intelligent, and hard-working team player who played a key role in our team and was the go-to person for almost any problem. I have seen few people who could match his skills at solving technical problems, coding and design.
Oren Hadri, Former Engineering Manager at InuitiveLinkedIn recommendation, Oct 2018
Yonatan is a highly talented and disciplined software developer, with an excellent background in both computer science and programming. He is a people-person, with remarkable empathy and ability to recognize when and where students and developers need help and further guidelines. He is also a very pleasant and good-spirited colleague.
Shimon Schocken, Computer Science Professor, Reichman UniversityLinkedIn recommendation, Oct 2018
Kotlin, Java, Spring Boot, OpenAPI, Kafka, Terraform, GitHub Actions, Docker, PostgreSQL, MySQL
Bottom of the building: ride back up to the lobby, or to the roof to get in touch.
ParkingSelected work
What I build on my own time.
