Senior Backend Engineer II, Authentication & Authorization

Brief Info About Vinted Our mission is to make second-hand the first choice, and we're looking for people who want to help us get there. Every day, we work together to help our members buy and sell pre-loved clothing and lifestyle items, giving each piece a second life – or even a third. The Vinted Group is made up of three business units that support this mission: Vinted Marketplace is Europe’s leading platform for second-hand fashion and a go-to destination for all kinds of pre-loved items, with a growing range of categories. Our platform connects millions of members across 20+ markets, helping great items find a new life. Vinted Go enhances the shipping experience with a vast network of over 500,000 pick-up and drop-off points, partnering with more than 60 carriers across Europe, with added services like item verification for peace of mind on high-value pieces. Vinted Pay is the newest part of the Vinted Group, dedicated to bringing secure, reliable payments to buyers and sellers across Europe. Seamlessly integrated into the Vinted app, it helps keep every transaction safe, efficient, and easy for our members. Founded in 2008 in Lithuania, Vinted began as a way for friends to find new homes for clothes they no longer needed. In 2019, we became Lithuania's first unicorn! Today, our headquarters remain in Vilnius, and we've grown with offices across Europe, supported by a team of over 2,000 people. Information About The Position Authentication and authorization underpin nearly every interaction on Vinted. They determine how members, employees, and services prove who they are, and what they are allowed to do. Today, these responsibilities span our core platform, dedicated identity services, gateways, service-mesh infrastructure, and workforce systems. We are evolving this landscape towards a shared identity model and an authorization platform that is secure, reliable, observable, and straightforward for engineering teams to adopt. We’re looking for a Senior Backend Engineer II to join the Authentication and Authorization team. You’ll work across two connected areas: Evolving authentication towards a consistent, federated identity model for members, employees, and systemsBuilding shared authorization capabilities that replace fragmented, service-specific solutions with common concepts, APIs, tooling, and decision observability This is neither a purely greenfield role nor a legacy-maintenance role. You’ll help extract existing functionality safely, improve production services, and build new platform capabilities. We’re looking for an experienced engineer, but not necessarily someone who already knows every part of identity and access management. What matters is strong engineering judgement, curiosity, and the ability to learn unfamiliar technologies and domains. You should be comfortable going deep into a technical problem, then zooming out to understand how the solution affects users, services, infrastructure, security, and other engineering teams. In this position, you’ll Design, build, and operate backend services supporting authentication, identity propagation, token exchange, authorization decisions, and policy managementHelp extract authentication functionality from existing systems while preserving feature parity, controlling rollout risk, and retiring legacy paths safelyContribute to stable identity and authorization contracts that allow services to evolve without depending on individual identity providers, token formats, or API implementationsBuild shared authorization capabilities, including a capability registry, policy APIs, decision logs, and tools for understanding who or what can access a resourceImprove supported integration paths - such as SDKs, libraries, conformance tests, documentation, and migration tooling - that make secure adoption easier for other teamsWork with Registration, Platform, Security, and product-domain engineers to define ownership boundaries, integration contracts, and safe migration plansKeep security-critical systems reliable and observable by contributing to SLOs, latency expectations, failure behaviour, monitoring, and operational responseTake ownership of complex areas of work from design through implementation, rollout, and production operationContribute to technical proposals and architectural decisions, helping the team understand the available trade-offsSupport other engineers through thoughtful code reviews, pairing, documentation, and knowledge sharingWrite, review, test, deploy, monitor, and troubleshoot production code About You You’re an experienced backend engineer who can take responsibility for difficult or unfamiliar problems. You don’t need to arrive with every answer. You’re comfortable saying, “I don’t know yet,” then learning enough to make a thoughtful decision and move the work forward.You can work across a wide technical surface without losing sight of the underlying problem. You know when to investigate deeply, when to involve someone else, and when a pragmatic solution is better than an elaborate one. We’d expect that: You have a strong track record of building and operating distributed backend systems in productionYou can take ownership of complex backend work, including design, delivery, rollout, and operational follow-throughYou know at least one programming language deeply and can transfer your engineering knowledge to unfamiliar languages and ecosystemsYou’re comfortable reasoning about APIs, data models, consistency, caching, concurrency, reliability, and security boundariesYou write clean, maintainable, well-tested code and contribute constructively to engineering standardsYou care about observability and understand that authentication and authorization systems must be explainable when something goes wrongYou can balance security, reliability, developer experience, delivery speed, and long-term maintainabilityYou communicate technical decisions clearly, including their risks and assumptionsYou collaborate effectively across team boundaries and help move shared work forwardYou share knowledge and make technical context easier for other engineers to accessYou’re curious, adaptable, and motivated by problems that require you to learn rather than simply repeat what you already knowYou have excellent written and spoken English It’s a plus if you have: Experience or familiarity with authentication and authorization conceptsKnowledge of OAuth 2.0, OpenID Connect, token exchange, identity federation, workload identitiesUnderstanding of RBAC, ABAC, policy-as-code, OPA/RegoExperience with service mesh technologies such as Envoy or IstioFamiliarity with Go, Ruby, infrastructure as code, and Git-based delivery workflowsWillingness to learn new technologies and apply them based on the problem at hand Work perks The opportunity to benefit from our share options programme25 working days of holidayAccess to all the tools & tech needed for workHome office support: we provide IT workstation equipment and a personal budget of up to €540 for home workplace furniturePrivate health insuranceMental and emotional health support through the Mindletic appFrequent team-building eventsA personal monthly budget for shopping on VintedThe opportunity to spend up to 90 days per year - 21 of which can be spent working outside of the EU - on workationA dog-friendly officeIn Vilnius office: Gym & in-house meals at friendly pricesIn Kaunas office: a monthly lunch allowance, and a once-a-week provided in-house lunch and breakfast Working at Vinted Individual Learning Budget We invest in your professional growth! As part of our commitment to continuous learning, we offer an annual learning budget to support your personal and career development through courses, certifications, workshops and more. Hybrid Work We’ve adopted a hybrid workplace model where 2 days in the office are recommended but not enforced. It’s up to you and your team to decide on the exact days you’ll spend working together in person. Equal Opportunity The Vinted Group is committed to building an inclusive workplace where people from all walks of life feel a sense of belonging. We welcome applications from people of all backgrounds, identities and life experiences. At Vinted, all applicants are treated fairly without regard to their race, age, religion or belief, sex, national origin, citizenship, gender identity, sexual orientation, disability, or any other protected characteristic. The gross monthly salary range for this position is: €6.542—€8.842 EUR