PHP / Backend Developer — FinTech & Payments Karlsruhe

PHP / Backend Developer — FinTech & Payments Location: Karlsruhe, Germany Tech Stack: PHP · Java · High-Performance Systems · AI-Assisted Development The Role: We are seeking a technically curious and analytical Backend Developer to build and maintain complex, business-critical systems within the FinTech and payments sector. This role is not defined by keyword-matching on a CV. We are looking for someone who can understand intricate problems, break them down logically, and build robust, reliable solutions — in an environment where performance, availability, and software quality are non-negotiable. Your Environment You will contribute to core systems that process financial transactions, where reliability and precision are paramount. Our engineering culture is modern, collaborative, and built on strong professional standards: Agile development methodologiesRegular code reviews and constructive technical feedbackComprehensive automated testing frameworksComplex backend and transaction-processing architecturesRigorous standards for code quality and maintainabilityDaily use of Claude and other AI development tools to accelerate and elevate our work AI is already an established part of our workflow — and its role will continue to grow. That said, we are looking for developers who can critically evaluate, understand, refine, and improve code generated by AI, rather than simply accepting output at face value. What We’re Looking For Proficiency in PHP is central to this role, but we welcome candidates with strong backend engineering foundations in Java or other equivalent languages. Technical breadth matters less than clarity of thought and a proven ability to solve hard problems. You may come from any background including: Software engineering or computer scienceMathematics, physics, or other analytical disciplinesProfessional experience in PHP, Java, or Python backend developmentMachine learning, AI, or research-focused rolesAgency, consultancy, or freelance software developmentSelf-taught or non-traditional career paths Our most successful hires have followed diverse routes — what unites them is sharp analytical thinking, genuine curiosity, and a clear interest in FinTech and payments. Core Qualities We Value Strong analytical and problem-solving ability — the foundation of everything we doSolid software engineering fundamentalsComfort navigating and improving complex systemsInterest in building high-performance, highly available applicationsConfidence working alongside AI tools — with the technical understanding to verify, correct, and enhance the code they produceCommitment to quality — valuing testing, code reviews, and maintainable designGrowth mindset — eager to learn and evolve your craft continuouslyGenuine interest in payments, banking, or FinTech Prior experience in banking or payments is advantageous, but not a requirement — enthusiasm and aptitude matter most.