Senior Software Engineer, AI-Native Development

qlub; Berlin; On-site; EUR 70,000 - 110,000; Full time

Job summary

qlub, a fintech scale-up, is hiring a Software Engineer in Berlin to build secure, scalable payment services and AI-powered workflows. You will own end-to-end development, integrate with POS and payment providers, and apply AI-assisted methods to accelerate delivery while upholding security and reliability.

English fluency is essential and experience in payments is a plus. You will collaborate with engineers, operations, and partners to turn frictionless payments into growth.

Qualifications

• Proven experience building production-grade software applications.
• Fluency in English is a must.
• Hands-on experience with Golang is required.
• Practical experience with LLM APIs, tool calling, retrieval-augmented generation, or agentic workflows.
• Experience designing secure, scalable software solutions.
• Strong knowledge of REST APIs, microservices, asynchronous processing, and distributed systems.
• Proficiency in databases, data modelling, and database design concepts.
• Experience with POS systems, payment providers, or complex third-party integrations.
• Experience building or integrating production AI applications.

Responsibilities

• Design, build, and operate secure, scalable payment services and integrations.
• Work with POS systems, payment providers, and third-party platforms.
• Use AI-assisted development tools across the software lifecycle to maintain quality.
• Develop AI-powered workflows that can retrieve data, call tools, and interact with systems.
• Implement permissions, guardrails, observability, and fallback mechanisms for agentic systems.
• Identify bottlenecks and improve speed, reliability, and cost efficiency of workflows.
• Write clean, tested, well-documented code following security best practices.
• Contribute to technical design discussions and engineering standards across the team.

Skills

Golang

REST APIs

Microservices

Distributed systems

AI/LLM tools

Tool calling

Retrieval augmented generation

Agentic workflows

Security

Testing & observability

Debugging & performance

English fluency

Job description

Why qlub

The end of a great meal shouldn't be the slow part. Waiting for the check, finding someone to take payment, splitting a bill by hand. qlub removes that friction. Guests scan a QR code and pay in seconds. No app, no download, no waiting.

From Pay-at-Table and Digital Menus to Order-and-Pay, Payment Links, and SoftPOS terminals, we handle the full payment experience so restaurants can focus on what they do best: great hospitality. Less friction means faster table turnover, smoother operations, and higher profit.

We're a fast-scaling fintech backed by Mastercard, Mubadala, e& and Shorooq. $72M raised, live across multiple markets worldwide, and headcount doubled in the past year. We're building the teams that take us to the next stage.

The role

qlub is scaling fast across markets worldwide, and we look for people who take real ownership of their work. As our next Software Engineer, you'll help drive our growth in engineering platforms by building, shipping, and delivering results from day one.

You'll work closely with engineers, operators and partners to turn frictionless payments into real growth for restaurants.

You will also use AI-assisted development practices throughout the software development lifecycle and contribute to AI-powered and agentic systems that can reason, retrieve information, use tools, and execute controlled workflows.

If you thrive in a fast-moving, build-from-scratch environment, this role is for you.

What you’ll own

• Design, build, and operate secure, scalable, and highly reliable payment services, including payment gateways, transaction processing, reconciliation, and settlement flows
• Build and maintain integrations with POS systems, payment providers, financial partners, and other third-party platforms
• Use AI-assisted development tools for discovery, implementation, debugging, testing, code review, documentation, and refactoring while maintaining strong engineering quality standards
• Design and develop AI-powered and agentic workflows that can retrieve data, call tools, interact with internal systems, and execute controlled actions
• Implement appropriate permissions, human approvals, guardrails, observability, auditability, and fallback mechanisms for agentic systems
• Identify performance bottlenecks and improve the speed, reliability, security, and cost efficiency of payment and AI-powered workflows
• Write clean, maintainable, tested, and well-documented code that follows software engineering and financial-system security best practices with AI
• Contribute to technical design discussions, architecture decisions, engineering standards, and continuous improvement across the team

Who you are

• You've done this before in a fast-moving, high-growth environment
• You move fast and make strong decisions with incomplete information
• You take real ownership and think like an operator, not a coordinator
• You're energized by hard problems in payments, hospitality, and customer experience
• You use AI development tools pragmatically to improve speed and quality without compromising security, maintainability, or engineering judgement
• You collaborate effectively with engineers, product teams, operations teams, and external technical partners

What you’ll need

• Proven experience in building production-grade software applications
• Fluency in English is a must
• Excellent problem-solving and communication skills
• Hands-on experience with Golang
• Practical experience with LLM APIs, tool calling, retrieval-augmented generation, or agentic workflows
• Experience designing and implementing secure and scalable software solutions
• Strong knowledge of REST APIs, microservices, asynchronous processing, and distributed systems
• Proficiency in databases, data modelling, and database design concepts
• Experience with POS systems, payment providers, or complex third-party integrations
• Experience building or integrating production AI applications
• Understanding of AI-system risks, including hallucinations, prompt injection, data leakage, non deterministic behaviour, and unsafe tool execution
• Experience with automated testing, observability, debugging, and performance optimization

Nice to have

• Experience in payments, fintech, hospitality tech, or a high-growth marketplace
• Experience with payment gateways, transaction processing, settlement, reconciliation, or chargeback systems
• Experience building AI agents that interact with APIs, databases, internal tools, or operational workflows
• Familiarity with model evaluation, prompt management, AI observability, guardrails, or LLM cost optimization
• Exposure to vector databases, embeddings, semantic search, or retrieval systems
• Experience with cloud platforms, containerized services, CI/CD, and infrastructure-as-code
• Familiarity with PCI DSS, data privacy, and secure software-development practices
• React/ modern frontend development experience

What we offer

• Real ownership over products that impact millions of diners and thousands of restaurants globally
• The opportunity to solve challenging problems in payments, hospitality, and customer experience
• A fast-moving environment where great ideas quickly become reality
• Close collaboration with experienced operators, builders, and industry experts
• A chance to leave a visible mark on one of the fastest-growing restaurant technology companies globally