PHP / Backend Developer — FinTech & Payments Karlsruhe

Optimus Search; Karlsruhe; Vor Ort; EUR 65.000 - 90.000; Vollzeit

Zusammenfassung

Optimus Search is seeking a PHP / Backend Developer for FinTech and Payments in Karlsruhe. You will build and maintain complex, business-critical systems where reliability and performance are non-negotiable. The role emphasizes clarity of thought, problem solving, and high-code quality in a modern engineering culture.

You should bring strong PHP skills, plus backend experience in Java or Python. Candidates from diverse technical backgrounds who thrive on challenging problems and enjoy

Qualifikationen

• Proficiency in PHP is central to this role.
• Backend engineering foundations in Java or Python are valued.
• Analytical mindset with the ability to solve complex problems is essential.
• Experience in FinTech or payments domains is a plus.

Kenntnisse

PHP

Backend engineering

Java

Python

Jobbeschreibung

PHP / Backend Developer - FinTech & Payments

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.

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:

• Regular code reviews and constructive technical feedback
• Comprehensive automated testing frameworks
• Complex backend and transaction-processing architectures
• Rigorous standards for code quality and maintainability
• Daily 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 science
• Mathematics, physics, or other analytical disciplines
• Professional experience in PHP, Java, or Python backend development
• Machine learning, AI, or research-focused roles
• Agency, consultancy, or freelance software development
• Self-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 do
• Solid software engineering fundamentals
• Comfort navigating and improving complex systems
• Interest in building high-performance, highly available applications
• Confidence working alongside AI tools - with the technical understanding to verify, correct, and enhance the code they produce
• Commitment to quality - valuing testing, code reviews, and maintainable design
• Growth mindset - eager to learn and evolve your craft continuously
• Genuine interest in payments, banking, or FinTech

Prior experience in banking or payments is advantageous, but not a requirement - enthusiasm and aptitude matter most.