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For Companies At a Glance
- Tasks: Build and maintain Kotlin services for our AI-powered SaaS platform.
- Company: Join Synthesized, a VC-backed company revolutionising software testing with AI.
- 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 - 48000 £ 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 are a VC-backed company supported by top investors. With strong traction across financial services, healthtech, and telecom, and a $90B+ market in sight, we are 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: Job Traffic
Contact Detail:
Job Traffic 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. Brush up on your skills by building small projects or contributing to open-source ones that use these technologies, as practical experience will make you stand out.
✨Tip Number 2
Understand the importance of clean architecture and resilience in backend development. Be prepared to discuss how you've implemented these principles in past projects during your conversations with us.
✨Tip Number 3
Get comfortable with PostgreSQL and tools like Liquibase for schema migrations. Having hands-on experience with these will not only help you in the role but also impress us during discussions about your technical background.
✨Tip Number 4
Showcase your collaborative skills by preparing examples of how you've worked with product managers and frontend engineers in the past. We value clear communication and teamwork, so be ready to share your experiences.
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 and Spring Boot. Include specific projects where you've implemented clean architecture and resilience, as well as any relevant work with PostgreSQL and CI/CD workflows.
Craft a Compelling Cover Letter: In your cover letter, express your enthusiasm for Synthesized and the role of Backend Developer. Mention how your skills align with their needs, particularly in building services that power UI features and your experience with OpenAPI and testing practices.
Showcase Relevant Projects: If you have GitHub repositories or other projects that demonstrate your backend development skills, include links in your application. Highlight any contributions to open-source projects or personal projects that showcase your expertise in Kotlin and cloud-native patterns.
Prepare for Technical Questions: Anticipate technical questions related to your experience with distributed systems, performance profiling, and JVM tuning. Be ready to discuss your approach to writing tests and how you ensure code quality through documentation and CI/CD practices.
How to prepare for a job interview at Job Traffic
✨Know Your Kotlin and Spring Boot
Make sure you brush up on your Kotlin and Spring Boot knowledge. Be prepared to discuss your past experiences building services with these technologies, as well as any challenges you've faced and how you overcame them.
✨Understand PostgreSQL and Data Modelling
Familiarise yourself with PostgreSQL schema design and data modelling. Be ready to explain your approach to schema migrations and how you've used tools like Liquibase or jOOQ in your previous projects.
✨Emphasise Testing and Documentation
Highlight your experience with writing unit and integration tests. Discuss how you practice documentation as code, and be prepared to share examples of how this has improved your team's workflow.
✨Show Your Collaborative Spirit
Since the role involves working closely with product managers and frontend engineers, be ready to talk about your collaborative experiences. Share examples of how you've communicated technical concepts to non-technical stakeholders and contributed to team discussions.
