Senior Backend Engineer, Trust & Safety

We are looking for a Senior Backend Software Engineer to join our Cozy team - the group building Vinted’s Moderation Platform. We build the internal platform that owns the logic and high-throughput systems deciding how reported items move through different states and how that information is presented to moderators in real time. Sitting within the Trust & Safety domain, we run a system with high data volume, complex workflows, and strong requirements around speed, traceability, and reliability. We help millions of users feel safe on Vinted.

We manage complex live state using live, snapshotted, and projected data patterns at large scale. Following a recent modularization effort, we are refactoring legacy paths and breaking out key microservices while balancing tight performance limits with experimentation. With massive data volumes, our engineers work on making flows highly observable, debuggable, and safe to change.

We operate as a strong, collaborative cross-functional product team: Web frontend engineers, four Backend engineers, a Software Engineer in Test (QA), and an EPDA group consisting of a Product Manager, Product Designer, Decision Scientist, and Engineering Manager.

• Restructure core moderation flows based on product requirements using a mix of live, snapshotted, and projected data
• Clean up legacy areas, restructure key flows, and prepare modular components for future microservice expansion
• Build and adapt unique experimentation systems to run advanced product and system tests
• Implement robust logging and monitoring to make high-volume flows observable, debuggable, and safe to change
• Balance strict technical requirements (latency, memory, speed) with domain needs (explainability, extensibility)
• Work closely within our Web, QA, and EPDA setup while providing mentorship and support to help nearby engineers grow
• Own your services: Monitor and improve backend service performance and stability. The team owns and monitors service-layer measurements (SLIs, SLOs, etc.) and participates in an on-call rotation, currently during working hours, though this may adapt to 24/7 in the future depending on operational needs.
• See your code affect 80+ million users almost instantly – our master branch is deployed straight to production on each merge, and we ship many times per day
• Work with a healthy mix of battle-tested and emerging technologies such as Ruby on Rails, Vitess, Redis, Kafka, MySQL, and more

• You know at least one language deeply (concurrency, memory, ecosystem) and are comfortable with API design, caching, and system architecture
• You take ownership of features and projects from start to finish, breaking complex state-management or routing problems down so others can tackle them too
• You mentor, onboard, and share knowledge generously
• Your code is clean, well-tested, and reviewed thoughtfully
• You document what you build - proposals, RFCs, and ADRs
• You are enthusiastic about AI technologies, use AI tools daily in your work, and proactively learn and experiment with how to adopt AI to boost engineering outcomes
• You care about observability and monitoring
• You connect the dots between deep technical work and the critical safety and business impact it has on millions of Vinted users
• You work well across teams and functions
• You use AI tools effectively for debugging, code optimization, and complex tasks — and you help others in the team get better at it too

• The opportunity to benefit from our share options programme
• 25 working days of holiday
• Access to all the tools & tech needed for work
• Home office support: we provide IT workstation equipment and a personal budget of up to 540 for home workplace furniture
• Private health insurance
• Mental and emotional health support through the Mindletic app
• Frequent team-building events
• A personal monthly budget for shopping on Vinted
• The opportunity to spend up to 90 days per year - 21 of which can be spent working outside of the EU - on workation
• A dog-friendly office
• In Vilnius office: Gym & in-house meals at friendly prices
• In Kaunas office: a monthly lunch allowance, and a once-a-week provided in-house lunch and breakfast