Senior Backend Engineer - Trust Detection

Depop is the community-powered circular fashion marketplace where anyone can buy, sell and discover desirable secondhand fashion. With a community of over 35 million users, Depop is on a mission to make fashion circular, redefining fashion consumption. Founded in 2011, the company is headquartered in London, with offices in New York and Manchester, and in 2021 became a wholly-owned subsidiary of Etsy.

Our mission is to make fashion circular and to create an inclusive environment where everyone is welcome, no matter who they are or where they’re from. Just as our platform connects people globally, we believe our workplace should reflect the diversity of the communities we serve. We thrive on the power of different perspectives and experiences, knowing they drive innovation and bring us closer to our users. We’re proud to be an equal opportunity employer, providing employment opportunities without regard to age, ethnicity, religion or belief, gender identity, sex, sexual orientation, disability, pregnancy or maternity, marriage and civil partnership, or any other protected status.

Depop’s Trust Detection squad plays a critical role in keeping our global community safe. We build proactive, scalable detection systems that identify harmful content and user behaviour early, enabling fast, fair, and effective moderation at scale. This is a cross-functional squad of Backend and Machine Learning Engineers working closely with Product, Data, Fraud and Trust and Safety partners. The team operates in a rapidly evolving problem space where threats change quickly and systems must continuously adapt.

As a Senior Backend Engineer in Trust Detection, you will have a unique opportunity to shape, evolve, and scale our detection capabilities. You will work on systems that are still maturing, influence how we productionise ML, and help establish strong engineering foundations as the domain grows. This role suits engineers who enjoy autonomy, are deeply curious, and thrive in collaborative, ambiguous problem spaces.

What you will be doing:

• Independently design and deliver backend solutions to medium-to-large problem spaces, from discovery through production and iteration.
• Build and evolve core detection services, pipelines, and APIs that operate at scale and under real-world adversarial conditions.
• Work hands-on with ML Engineers and ML Scientists to productionise models and improve detection pipelines, monitoring, and iteration loops.
• Take end-to-end ownership of your work, including design, implementation, testing, observability, and operational support.
• Contribute to shaping technical direction within the team, improving system design, reliability, and developer experience.
• Operate in an experiment-led environment, helping define hypotheses, success metrics, and feedback loops.
• Collaborate closely with Product, Fraud, Trust and Safety, and other Engineering teams to ensure solutions are well scoped and well understood.
• Actively contribute to continuous improvement through retrospectives, post-incident reviews, and technical discussions.
• Mentor and support other engineers in the team, raising the overall quality of delivery.

Why this role is exciting:

• You will help shape and scale detection systems that are still evolving rather than joining a fully fixed platform.
• You will work closely with ML Scientists without needing to be an ML specialist.
• You will have real ownership over meaningful problem areas.
• You will see direct, measurable impact from your work on the safety of millions of users.
• You will join a team that values experimentation, learning, and pragmatic engineering excellence.

What are we looking for:

• Strong backend engineering fundamentals with experience independently delivering production systems.
• Proficiency in at least one backend language such as Scala, Java, or Python, with the ability to learn new languages quickly.
• Experience working with data-intensive systems, including designing, consuming, and evolving data models across services.
• Experience building or operating event-driven systems, such as producing and consuming events or messages in distributed architectures.
• Experience building scalable and reliable services and APIs.
• A strong sense of ownership paired with effective collaboration and communication.
• Comfort working in ambiguous problem spaces and proactively shaping solutions.
• Solid testing practices across unit and integration levels.
• Experience working in a DevOps-oriented environment including CI/CD and production monitoring.

Helpful experience, but we value learning just as much:

• Experience running, maintaining, or evolving ML-powered systems in production.
• Experience in experiment-led or hypothesis-driven teams with strong data and insights practices.
• Prior work in Trust and Safety, fraud, abuse detection, or moderation systems.
• Experience in marketplace or eCommerce environments.
• Hands-on experience with message brokers or streaming platforms such as Kafka or similar technologies.
• Experience with Docker and Kubernetes.
• Familiarity with AWS infrastructure and infrastructure-as-code tooling.

Additional Information:

• Health + Mental Wellbeing: PMI and cash plan healthcare access with Bupa, subsidised counselling and coaching, Cycle to Work scheme, Employee Assistance Programme (EAP) for 24/7 confidential support.
• Work/Life Balance: 25 days annual leave with option to carry over up to 5 days, 1 company-wide day off per quarter, impact hours for volunteering, fully paid 4 week sabbatical after 5 years of service.
• Flexible Working: MyMode hybrid-working model with Flex, Office Based, and Remote options.
• Family Life: 18 weeks of paid parental leave for full-time regular employees, IVF leave, shared parental leave, and paid emergency parent/carer leave.
• Learn + Grow: Budgets for conferences, learning subscriptions, and mentorship programmes.
• Your Future: Life Insurance (financial compensation of 3x your salary), pension matching up to 6% of qualifying earnings.
• Depop Extras: Employees enjoy free shipping on their Depop sales within the UK, special milestones are celebrated with gifts and rewards!