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- Tasks: Join us as a Backend Developer to build and scale our AI-powered SaaS platform.
- Company: Synthesized is revolutionising software testing with AI, trusted by major global companies.
- Benefits: Enjoy hybrid work, generous pay, personal development budget, and 33 days paid leave.
- Why this job: Shape architecture, own features, and collaborate in a friendly, inclusive environment.
- Qualifications: Experience in Kotlin/Java, Spring Boot, PostgreSQL, and CI/CD tools required.
- Other info: Work in a vibrant Shoreditch office with great team events and snacks!
The predicted salary is between 28800 - 42000 £ per year.
About Us
Synthesized is transforming how the world tests software with AI. Trusted by global leaders like Deutsche Bank, UBS, and the European Commission, our AI-powered platform enables teams to generate high-quality test data and test cases in seconds—slashing costs, accelerating delivery, and eliminating reliance on production data. We're a VC-backed company supported by top investors. With strong traction across financial services, healthtech, and telecom, and a $90B+ market in sight, we're scaling fast in 2025 and beyond.
The Role
We’re looking for a Backend Engineer (Kotlin) to evolve and scale the control-plane of our SaaS platform. With customer adoption climbing, we need extra fire-power to extend core services and keep pace with new feature demand. Reporting to the Backend Team Lead, you’ll build services that power everything the UI depends on. You’ll work closely with Product Management on feature design and pair with frontend engineers. The role offers plenty of scope to shape architecture, own features end-to-end, and put your stamp on architectural decisions that drive the product forward.
Key Responsibilities
- Design, implement and maintain Spring Boot services in Kotlin, with a focus on clean architecture and resilience.
- Model data in PostgreSQL, own schema migrations with Liquibase, and access data through jOOQ.
- Treat the OpenAPI contract as the single source of truth. Co-author, review and enforce it across teams, automate server/client generation.
- Practice shift-left testing: write unit and integration tests alongside your code.
- Practice documentation as code: write documentation for new features alongside your code.
- Contribute to and refine our CI/CD workflow on GitHub Actions.
- Collaborate daily with the Product Manager, Team Lead and frontend engineers to de-risk stories, clarify edge cases and deliver iterative value.
- Participate in code reviews and architecture discussions, sharing knowledge and mentoring when opportunities arise.
- Help monitor production with logs/metrics, triaging incidents and feeding learnings back into design and tests.
About You
- Professional experience building Kotlin (or Java) services on Spring Boot in production.
- Solid knowledge of PostgreSQL schema design, indexing, SQL queries and migration tools (Liquibase or similar) and fluency with jOOQ or similar tools for type-safe data access.
- Comfortable writing tests (JUnit, Testcontainers, MockMVC) and using code-coverage metrics to guide improvements.
- Hands-on with OpenAPI / Protobuf and code-generation workflows; you value strongly typed contracts between services and UI.
- Familiar with GitHub and GitHub Actions (or similar) for CI/CD and environment automation.
- Understanding of cloud-native patterns (containers, REST/gRPC APIs, observability).
- Good grasp of distributed-systems pitfalls, which is relevant to our remote-agent/control-plane topology.
- Practical experience with performance profiling and JVM tuning is a plus.
- Understanding basics of front end development (full stack skills) is a strong plus.
- Clear communicator who enjoys whiteboarding with product and frontend peers and can explain trade-offs to both technical and non-technical stakeholders.
- Continuous learner who values clean code and incremental delivery.
What We Offer
- Wonderful office in the heart of Shoreditch, hybrid 3-days
- Generous cash compensation and share options
- Flexible work hours
- Personal development budget (coaching, courses, events)
- Comprehensive health, vision, and dental plan coverage
- 33 days paid leave per year including flexible national holidays
- Snacks and drinks provided weekly
- Working alongside great people in a friendly and respectful environment
- Company events, regular team socials, and international trips
Equal Opportunities
We are committed to an inclusive and diverse workplace at Synthesized. Synthesized is an equal opportunity employer. We do not discriminate based on race, ethnicity, color, ancestry, national origin, religion, sex, sexual orientation, gender identity, age, disability, veteran status, genetic information, marital status or any other legally protected status.
Backend Developer (Kotlin) employer: Synthesized
Contact Detail:
Synthesized Recruiting Team
StudySmarter Expert Advice 🤫
We think this is how you could land Backend Developer (Kotlin)
✨Tip Number 1
Familiarise yourself with Kotlin and Spring Boot if you haven't already. Since the role specifically requires experience in these technologies, being able to discuss your past projects or any personal projects using them will show your passion and readiness for the position.
✨Tip Number 2
Brush up on your PostgreSQL skills, especially schema design and migrations with Liquibase. Being able to demonstrate your understanding of database management and how it integrates with backend services will set you apart from other candidates.
✨Tip Number 3
Prepare to discuss your experience with CI/CD workflows, particularly using GitHub Actions. Highlighting any specific instances where you've contributed to improving deployment processes can showcase your proactive approach and technical expertise.
✨Tip Number 4
Engage with the community around Kotlin and Spring Boot. Whether it's through forums, GitHub contributions, or local meetups, showing that you're an active participant in the tech community can demonstrate your commitment to continuous learning and improvement.
We think you need these skills to ace Backend Developer (Kotlin)
Some tips for your application 🫡
Tailor Your CV: Make sure your CV highlights your experience with Kotlin, Spring Boot, and PostgreSQL. Include specific projects where you've implemented these technologies, as well as any relevant achievements that demonstrate your skills.
Craft a Compelling Cover Letter: In your cover letter, express your enthusiasm for Synthesized and the role of Backend Developer. Mention how your background aligns with their mission to transform software testing with AI, and provide examples of how you've contributed to similar projects in the past.
Showcase Your Technical Skills: When detailing your technical skills, be specific about your experience with tools like Liquibase, jOOQ, and GitHub Actions. Highlight any relevant certifications or courses you've completed that relate to backend development and CI/CD workflows.
Prepare for Technical Questions: Anticipate technical questions related to distributed systems, performance profiling, and cloud-native patterns. Be ready to discuss your approach to writing tests and maintaining clean code, as these are key aspects of the role.
How to prepare for a job interview at Synthesized
✨Showcase Your Kotlin Expertise
Make sure to highlight your professional experience with Kotlin and Spring Boot during the interview. Be prepared to discuss specific projects where you've implemented these technologies, focusing on clean architecture and resilience.
✨Demonstrate Your Database Skills
Since PostgreSQL is a key part of the role, be ready to talk about your experience with schema design, indexing, and SQL queries. You might also want to share examples of how you've used Liquibase for schema migrations.
✨Emphasise Testing Practices
The company values shift-left testing, so come prepared to discuss your approach to writing unit and integration tests. Mention any tools you've used, like JUnit or Testcontainers, and how you ensure code quality through testing.
✨Communicate Clearly and Collaboratively
As a backend developer, you'll need to work closely with product managers and frontend engineers. Practice explaining technical concepts in simple terms and be ready to discuss how you've collaborated with cross-functional teams in the past.
