Senior Backend Engineer - Germany

About Klar

We're turning one of the world's largest underbanked markets into something fairer, simpler, and more transparent. 

7 million users served since 2019. Uber's first global credit card, built right here in Mexico. Klar Empresarial, a brand-new B2B solution — Klar Empresarial — bringing agile credit and smart accounts to SMEs who've been ignored by traditional banks for too long.

And a full banking license on the horizon, because our customers asked for it and we listened.

We move fast, we think big, and we go all in, because as our CEO puts it: "Growing doesn't always mean going further. Sometimes it means going deeper." 

Behind all of it is a team of 30+ nationalities, working across Mexico City, Berlin, and Argentina, obsessed with building financial products that are simpler, faster, and fairer than anything that came before.

This is Klar, and we're seeking the people who'll write the next chapter.

Our people

If you join us at Klar, you’ll be welcomed to a team that is rich in many talents and we are very proud! With our head office in Mexico City, and remote tech hubs in Berlin and Argentina, we are always learning something new about another culture or language. With so many people from different backgrounds and walks of life (young professionals, parents, LGBTQ+, neurodivergence), you’ll definitely find your people here! 

Our values 

• Ownership - We own our successes & our failures as a team.
• Excellence - We do everything to the best of our ability & always seek to achieve a new level of excellence in our work.
• Inclusion - We believe we are stronger together and actively work to promote a safe, diverse, inclusive, and respectful culture.
• Customer Obsession - We understand the value Klar can bring to its customers & it’s always at the forefront of our decisions.
• Klarity - We communicate clearly & with authenticity. It’s in our name & it’s what we do.

About the Role

This is a full-time remote opportunity for candidates based in Germany.

Our Credit engineering team owns the Loan Service, the system of record responsible for a user's entire borrowing journey — from the moment a loan offer is presented, through disbursement, fee accrual, repayment, delinquency, and write-off.

We are looking for a Senior Software Engineer to help us design, build, and scale the backend systems that power Klar's credit products (personal loans, Buy Now Pay Later and credit lines/CCK). You will work on financial-grade, high-throughput systems that must be correct, auditable, while integrating with a broader ecosystem of microservices (Risk, Credit Scoring, KYC, Balance, Transfers, Notifications).

What you can expect: 

• Design, implement, and own backend services and APIs across the loan lifecycle, from technical design through production rollout.
• Write clean, well-tested, maintainable Java code following the team's engineering standards (checkstyle, code review, high test coverage).
• Build and evolve Kafka-based event producers/consumers that keep credit, accounting, and risk systems in sync.
• Author safe, backward-compatible database migrations for a system with large, continuously-written tables.
• Collaborate closely with Risk, Data Science, Product, and Accounting stakeholders to translate business and regulatory requirements into system behavior.
• Participate in code reviews, design discussions, and incident response; mentor other engineers on the team.
• Write and maintain unit, integration, and contract tests to guard the correctness of financial calculations and state transitions.

What You'll Work On:

• Loan lifecycle engine: offer generation, loan creation, disbursement, fee accrual, repayment (manual and automatic), prolongation, and loan write-off.
• Risk & policy integration: enforcing credit limits and rule-engine-driven eligibility policies defined by the Risk team, and integrating credit scoring and KYC signals into loan offer decisions.
• Financial correctness: precise monetary calculations (principal, fees, VAT, interest), repayment ordering, and accounting-consistent state transitions regulatory requirements.
• Product expansion: extending support for new credit products such as personal loans, credit lines, and BNPL, each with distinct billing cycles and repayment rules.
• Platform reliability: observability (Prometheus/Grafana, OpenTelemetry), database migrations at scale (Flyway on high-volume tables), and safe rollout of changes to a system handling millions of active loans.

What we are looking for:

Must-have:

• 5+ years of professional backend software development experience.
• Strong proficiency in Java (Java 17/21) and the Spring Boot ecosystem (Spring Data JPA, Spring Kafka, Spring Retry).
• Solid experience designing and operating REST APIs in a microservices architecture, including API documentation (OpenAPI/Swagger).
• Hands-on experience with relational databases (PostgreSQL preferred) and schema migration tools (Flyway or similar), including migrations on large, high-traffic tables.
• Experience building event-driven systems with message brokers such as Apache Kafka (producers, consumers, retry/error handling).
• Strong grasp of testing practices: JUnit 5, Mockito, AssertJ, Testcontainers, and writing tests for asynchronous/event-driven flows.
• Comfort working with monetary/financial calculations that demand precision and correctness (e.g., BigDecimal, rounding, fee/interest computation).
• Familiarity with containerized local development (Docker, Docker Compose) and CI/CD pipelines.
• Strong communication skills and the ability to work with cross-functional, non-technical stakeholders (e.g., Risk and Finance teams).

Nice-to-have:

• Experience in fintech, lending, or banking systems, especially loan origination, servicing, or collections.
• Familiarity with accounting/ledger concepts (double-entry bookkeeping, subledgers) or regulatory standards such as IFRS 9.
• Experience with Protocol Buffers, MapStruct, Lombok, or distributed-lock libraries (e.g., ShedLock).
• Experience with observability stacks (Prometheus, Grafana, OpenTelemetry) and operating services at scale (millions of users/requests).
• Exposure to rules-engine-driven decisioning or risk policy systems.

Our offer to you

• Competitive salary based on performance and experience
• Chance of earning Klar stock options
• 26 days of paid vacation per year
• Computer devices
• Wellhub subscription to offer mental and physical health
• Sponsored coaching and therapy sessions via a Mental Health platform 
• Training budget to upskill your learning
• Health insurance & Pension scheme
• BVG Corporate ticket
• Berlin office if you prefer to work onsite
• International work environment with amazing and highly skilled people
• A world class team that helps you evolve your skills in areas you're interested in

Klar is a safe place for everyone!

We trust our highly skilled and diverse team and we’re committed to creating a welcoming and inclusive environment for new talents to flourish. We value diversity and welcome all applications regardless of gender, nationality, ethnic and social origin, religion/belief, physical abilities, age, sexual orientation and identity.

Should you require any accommodations through the recruitment process, please don’t hesitate to let us know how we can help!