Yonatan Karp-Rudin Staff Software Engineer

Staff Software Engineer · Payments, risk, and compliance

I turn messy backend domains into systems teams can own.

I work where product rules, vendor integrations, event flows, and operational risk meet. Recently that has meant compliance services, risk orchestration, API contracts, internal tools, and migrations that leave teams with clearer ownership.

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Role Staff backend engineer
Current scope Payments and compliance platforms
Evidence Boundaries, contracts, tooling, and recovery paths
Portrait of Yonatan Karp-Rudin

Yonatan Karp-Rudin

Staff Software Engineer, Payments Builder · explainer · team multiplier

How I multiply a team

01

Clarify the problem

Turn ambiguity into boundaries, contracts, examples, and failure modes.

02

Build the path

Ship the integration, migration plan, internal tool, or reference implementation.

03

Leave leverage

Leave specs, monitors, templates, and upstream fixes that outlive the handoff.

Payments, risk, compliance Kotlin/JVM, Kafka, OpenAPI OSS, docs, templates

Proof

Examples of staff-level leverage beyond ticket delivery.

Compliance platform

Creating a new service boundary for compliance workflows.

Problem
Transaction monitoring, screening, and sanction checks crossed product rules, vendor behavior, alerts, and audit expectations.
Leverage
I authored the technical spec and interfaces, led the ComplyAdvantage integration, and covered Kafka DLT alerts, settlement reports, and compliance states in the service design.
Result
Scattered operational knowledge became a service teams can reason about, monitor, and recover.

Risk architecture

Moving risk work toward explicit orchestration and contracts.

Problem
Risk decisions depended on multiple services, fraud providers, recurrent identification, tokenization, and direct debit behavior.
Leverage
I co-designed the Risk Orchestrator, pushed OpenAPI-first contracts across risk services, led the Ravelin integration, and authored the Buyer Risk Assessment target architecture.
Result
Risk changes gained a clearer coordination model across providers, payment behavior, and service boundaries.

Engineering leverage

Turning repeated operational friction into shared tooling.

Problem
Platform work gets expensive when incidents, cronjobs, migrations, and service setup depend on private memory.
Leverage
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.
Yonatan Karp-Rudin

How I work

I like the moment when a domain becomes specific enough to build.

The hard part of backend engineering is often not choosing a framework. It is finding the real boundary: which team owns the rule, 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 where I tend to be useful. I ask 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.

I care about strong implementation, but the higher leverage is making the system easier for the whole team to operate, extend, and argue about with evidence.

Works across Backend systems, Kotlin/JVM, service design, OpenAPI, Kafka, internal tools, docs, and OSS
Bias toward Shared understanding, small useful abstractions, boring reliability, and explanations that survive handoff

Track record

Backend roles shaped by domain ownership and reusable engineering systems.

Oct 2025 - Present

Staff Software Engineer

Billie, Berlin, Germany

Staff Software Engineer - Payments

Owns payments/compliance platform reliability across service boundaries, vendor integrations, migration work, and operational tooling.

Apr 2025 - Oct 2025

Staff Software Engineer

Billie, Berlin, Germany

Staff Software Engineer - Risk

Led Staff-level risk platform work around orchestration, fraud integrations, tokenization, and event-driven architecture.

See the full history on the CV →

Selected work

Public work that turns repeated problems into reusable material.

01

Self-hosted tool

TaleKeeper

Self-hosted TTRPG session recorder that turns live table audio into searchable campaign memory. The Python/FastAPI backend handles transcription, speaker diarization, and summary generation; the Svelte 5 frontend keeps review and session lookup usable at the table.

Docs
02

Open source library

ff4k

Kotlin Multiplatform feature flags library built after an upstream ff4j Jakarta migration stalled before release. It focuses on typed DSL configuration, JDBC/R2DBC/SQLite storage options, and coroutine-safe context propagation so feature decisions can stay explicit across backend boundaries.

Docs
03

Upstream contribution

openapi-generator

Added Spring Boot 4 and Jackson 3 support for the Kotlin Spring generator, then followed through on template regressions that surfaced around Retrofit, Jackson converters, and hashmap model generation. The work spans 10 upstream PRs across generator behavior, test fixtures, and compatibility paths.

GitHub
04

Technical writing / docs

kotlin-design-patterns

Software design patterns implemented in idiomatic Kotlin. Actively maintained with MkDocs documentation site.

Website

View all projects →

Writing

Writing is how I turn hard-won context into something other people can reuse.

View all blog posts →

Recommendations

What people notice after working with me.

Blake Irvin
Blake Irvin Leading Observability Engineering at SumUp
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.
Oren Hadry
Oren Hadry Former Engineering Manager at Inuitive
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.
Shimon Schocken
Shimon Schocken Computer Science Professor, Reichman University
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.

Contact

If your team needs clarity and code, let's talk.

I am most useful in Staff+ backend roles where the job is to ship the system and leave the team better at owning it.

  1. Permanent Staff+ backend roles
  2. Backend architecture advisory
  3. OSS, writing, and teaching

I am useful when the team needs clarity as much as code.

  • Important work with fuzzy ownership
  • Backend systems carrying hidden context
  • Repeated problems that need reusable tooling
  • Teams that need a pathfinder and teacher
Based in Berlin, Germany
Best for Teams that need clarity, code, and leverage
GitHub github.com/yonatankarp LinkedIn linkedin.com/in/yonatankarp