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For Companies At a Glance
- 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 international trips.
The predicted salary is between 36000 - 60000 £ 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) (City of London) employer: Synthesized
Contact Detail:
Synthesized Recruiting Team
StudySmarter Expert Advice 🤫
We think this is how you could land Backend Developer (Kotlin) (City of London)
✨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 projects or any relevant work you've done with them will show your passion and readiness for the position.
✨Tip Number 2
Brush up on your PostgreSQL skills, especially schema design and migrations. Being able to talk about your experience with Liquibase or similar tools will demonstrate your capability to handle the database aspects of the role effectively.
✨Tip Number 3
Prepare to discuss your experience with CI/CD workflows, particularly using GitHub Actions. Highlighting any past projects where you've implemented automated testing or deployment processes will showcase your understanding of modern development practices.
✨Tip Number 4
Showcase your collaborative skills by preparing examples of how you've worked with product managers and frontend engineers in the past. This will help illustrate your ability to communicate effectively and contribute to a team-oriented environment.
We think you need these skills to ace Backend Developer (Kotlin) (City of London)
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 the role at Synthesized. Mention how your background aligns with their mission of transforming 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, focus on your experience with CI/CD workflows, unit testing, and cloud-native patterns. Be specific about the tools you've used, such as GitHub Actions, JUnit, and Liquibase, to demonstrate your hands-on expertise.
Prepare for the Interview: If you get called for an interview, be ready to discuss your previous work in detail. Prepare to explain your architectural decisions, how you handle edge cases, and your approach to collaboration with product managers and frontend engineers.
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 how you tackled challenges and contributed to the overall architecture.
✨Demonstrate Your Understanding of Databases
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 even want to prepare a few examples of how you've managed schema migrations using Liquibase or similar tools.
✨Emphasise Testing Practices
The company values shift-left testing, so come prepared to discuss your approach to writing unit and integration tests. Share examples of how you've used tools like JUnit and Testcontainers to ensure code quality and reliability in your previous projects.
✨Communicate Clearly and Collaboratively
As collaboration is crucial for this role, practice explaining technical concepts in a way that non-technical stakeholders can understand. Be ready to discuss how you've worked with product managers and frontend engineers in the past to deliver value and clarify edge cases.
