Backend Engineer Ruby (fmd) Mid-Level

Berlin - Germany

Yearly Salary: EUR 55000 - 65000

Posted on: Yesterday

Vacancies: 1 Vacancy

Job Summary

We co-founded and led Viafintech (Barzahlen) to 100 FTE one of the most successful German fintechs active in 17 markets across the EU and USA and sold it in 2021 for a three-digit million amount to NYSE-listed Paysafe Group.

Now were off to our next venture. This time were building a global champion for prepaid products: gift cards (Apple Amazon Google) airtime and eCash all in one simple API. Think of finperks as a stripe/adyen for all prepaid products and payments.

We started in summer 2025 and in just a few months we have already onboarded 700 brands and our first client goes live by the end of the year.

Many people completely underestimate the market size: about 600bn sold per year today going to 1.8tn by 2028.

Instead of 5 players in the chain (brand issuing tech provider global distributor local distributor client) we connect brands directly with clients via the finperks platform. Today 95% of prepaid is still sold in the Global North; we believe that for the gig economy to monetize the Global South prepaid will be key - from Netflix and Google to Apple and Uber.

Were a team of 8 in Berlin-Charlottenburg. A mix of our best people from the last journey and brilliant new joiners. High ownership. Low ego. Kind humans. We ship fast help each other and celebrate wins.

Join early. Help build the global champion for prepaid.

Tasks

As a Software Engineer youll build the core platform that connects global brands with clients across multiple markets.

You will:

Design and implement RESTful APIs that handle gift card distribution transaction processing and inventory management at scale
Build robust maintainable backend systems that power our prepaid product platform - from brand integrations to client-facing services
Work with PostgreSQL to design efficient schemas optimize queries and ensure data integrity for financial transactions
Integrate with local/global brand partners (Rewe Amazon Zalando etc.) and payment providers through various APIs and protocols
Write efficient code and optimize database queries to handle growing transaction volumes
Implement comprehensive test coverage (RSpec) and maintain high code quality standards
Instrument code with proper logging and monitoring using our ELK stack
Work closely with frontend engineers infrastructure team and product to deliver features that delight our clients
Youll focus on backend but youll occasionally work across the full stack - were a small team where backend engineers ship UI fixes and frontend engineers optimize queries when needed

Requirements

Youll need:

Ruby (on Rails) Mastery: 3 years building production applications with strong understanding of Ruby conventions
Database Skills: Solid experience with PostgreSQL including schema design query optimization and transactions
API Design: Proven experience designing and building RESTful APIs that are intuitive well-documented and performant
AWS Familiarity: Understanding of AWS services and cloud-native application development
Testing: Strong commitment to test-driven development with RSpec or similar frameworks
Version Control: Proficient with Git workflows and collaboration practices
Problem Solver: You enjoy tackling complex business logic and finding elegant technical solutions
Communication: Strong English skills; German is a plus

Nice to have:

Experience in FinTech payment processing or e-commerce
Knowledge of background job processing (Solid Queue/Delayed Job/Sidekiq)
Familiarity with ELK stack for logging and debugging
Experience with Docker and containerized applications
Understanding of security best practices for financial applications

Benefits

Learn from experienced Engineers: Recieve constant feedback while having eye-level discussion
Ownership from Day One: Make architectural decisions and own features end-to-end with real impact
Shape the Product: Influence product direction by working directly with clients like N26 Trade Republic and major global brands
Modern Development Practices: Clean codebase comprehensive testing code reviews and continuous deployment
Competitive Package: Attractive salary
Berlin Lifestyle: Office in Charlottenburg with flexibility for hybrid work arrangements

Ready to build backend systems for the next FinTech Unicorn

We are looking for builders ready for an ambitious journey. Expect tough challenges plenty feedback constant change on-call duty and frequent return youre getting lots of opportunity to grow the smartest people you have worked with on your team and recognition for doing your best work.
If you need clarity on every task avoid ambiguity at all costs or prefer established processes over figuring things out - this isnt the place. But if youre energized by zero-to-one building thrive when shipping fast matters more than perfection and want ownership over following playbooks Apply Now!