We are Billie, the leading provider of Buy Now, Pay Later (BNPL) payment methods for businesses, offering B2B companies innovative digital payment services and modern checkout solutions. We are to create a new standard for business payments and have made it our mission to simplify the purchasing experience for all businesses making it a tool for growth. Our solutions are based on proprietary, machine-learning-supported risk models, fully digitized processes and a highly scalable tech platform. This makes us a deep-tech company building financial products, not the other way around. We love building simple and elegant solutions and we strive for automation and scalability.

Software Engineer (PHP & JVM/Kotlin) (f/m/d)

At Billie, we're not just building payment solutions; we're architecting the future of B2B commerce. We empower businesses to operate with unprecedented freedom and efficiency, leveraging a sophisticated, machine-learning-driven platform that streamlines financial transactions. We are a team of deep-tech innovators, driven by the challenge of transforming complex financial realities into simple, elegant, and automated experiences. If you're a polyglot engineer with a strong foundation in both PHP and JVM technologies, eager to navigate and shape our evolving Payments domain, this is your opportunity to write a significant chapter in our story.

Your Chapter at Billie: The Role

As a Software Engineer focusing on both PHP and JVM/Kotlin, you will be an integral part of our engineering team within Billie's Payments domain. This domain is the beating heart of our business, covering the intricate movement of funds – from initiation and settlement to transaction identification, reconciliation, and reporting. You will be instrumental in enhancing our current systems (where PHP plays a significant role) while actively contributing to our future, built upon a cutting-edge microservices architecture primarily using JVM/Kotlin. This role is for someone who thrives on understanding diverse technical and product landscapes, influencing architectural decisions, and applying Domain-Driven Design (DDD) principles across different stacks to deliver resilient and scalable financial products. You will tackle complex challenges, bridging the present and future state of our technology landscape.

Crafting the Future: What You’ll Do

• Full-Stack Backend Development: Design, develop, test, deploy, maintain, and improve our mission-critical payment systems, utilising your expertise in both PHP (e.g., Symfony) and JVM technologies (primarily Kotlin/Spring Boot).

• Architectural Contributions: Collaborate with Senior Staff Engineers to design and refine the architecture of our high-throughput, fault-tolerant payment systems. This means contributing to strategic decisions that pave the way for scalable, secure, and resilient operations within the Payments domain, across both existing and new stacks.

• Strategic Modernisation: Take ownership of improving and changing the current status quo, whether through smart refactoring of existing PHP applications or the addition of new services in JVM/Kotlin, ensuring seamless evolution.

• Leading Microservices Adoption: Actively participate in our journey towards a truly decoupled microservices architecture, contributing to the conceptualisation, building, and deployment of new services that facilitate, orchestrate, and monitor all money movements behind Billie's products.

• Championing Domain-Driven Design: Be instrumental in fostering a deep understanding and practical application of DDD across the team, guiding the design of software that intimately mirrors our business domains, ensuring clarity, maintainability, and strategic alignment, particularly for core payment functionalities.

• Engineering Excellence: Drive continuous improvement in our engineering practices, contributing to the evolution of our CI/CD pipelines, advocating for fast feedback loops, and ensuring a culture of quality and automation across the Payments domain.

• Cross-Functional Collaboration: Your impact will extend beyond code. You’ll work hand-in-hand with product managers, data scientists, and other engineering teams, translating complex business needs into elegant technical solutions and delivering features that directly accelerate Billie's success by evolving our payment capabilities.

• Mentorship & Knowledge Sharing: Mentor and train team members, share knowledge across teams, and perform thorough code reviews, contributing to a high-performing engineering culture.

Your Toolkit & Experience: What You’ll Bring

• Dual-Stack Proficiency: Strong professional production development experience in both PHP (e.g., Symfony or similar frameworks) and JVM languages (with a strong focus on Kotlin and Spring Boot). While you might have a deeper expertise in one, you are proficient and comfortable working in both environments.

• Impactful Engineering: Typically 5+ years of hands-on software engineering experience, having built and scaled highly available, resilient systems in production environments.

• Architectural Acumen: Proven track record of contributing to and influencing architectural designs for distributed systems and microservices. You enjoy tackling complex system design challenges.

• DDD Conviction: A deep understanding of Domain-Driven Design principles and the ability to apply them effectively in your day-to-day work.

• Cloud & Microservices Experience: Working experience with Microservices and Cloud-based development environments (e.g., AWS, event-driven architecture, CQRS).

• Agile Practices: Strong conviction towards and practical experience with Agile engineering practices such as Test-Driven Development (TDD), mobbing, and pair programming.

• Ownership & Drive: Be self-organised, self-driven, and willing to take end-to-end ownership of initiatives from start to finish.

• Communication: Excellent written and verbal communication skills in English, with the ability to articulate intricate technical concepts clearly to diverse audiences, fostering effective collaboration.

What we offer:

• Challenging and impactful work that drives personal and professional growth

• One of the best Virtual Shares Incentive Programs in the market, so that everyone at Billie is invested in our success

• Flexible work hours and trust in your ability to deliver, empowering you to take control of your work-life balance

• A hybrid working approach that allows you to work from home for up to 3 days per week

• Enjoy 30 days vacation per year on top of paid public holidays, sabbatical opportunities, and extra child sickness leave for parents.

• Our “Catch a Ride with Billie” program that enables discounted access to Berlin Public Transport (BVG), Deutschland-Ticket, OR JobRad

• A yearly development budget to broaden your skill set and horizons

• Free German group classes

• An English-speaking, multicultural team with more than 40 nationalities

• Building meaningful connections with your colleagues through company and team events, interest groups, the Billie run club, game nights, and more, powered by our Formula Fun Team!