Senior Backend Engineer - Experimentation Platform

Think it, build it, ship it, tweak it - that’s our rhythm.
Spotify’s Confidence team is a startup inside Spotify, building the next‑generation experimentation platform used by hundreds of internal teams - and now being prepared for external customers. You’ll join a small, senior crew of backend, data, and research engineers who care deeply about correctness, performance, and design. We move fast and carefully: ship small, reversible changes with strong safeguards, measure impact, and iterate. We operate multi‑tenant, high‑scale services where reliability and developer experience are first‑class. You’ll build, run, and refine these systems end‑to‑end, partnering with Product, Data Science, and our Customer Success team to turn real‑world signals into product improvements. We keep process light and hold a high bar for ownership and impact.

What You'll Do

• Ship and iterate quickly
• Design, build, and operate high‑throughput, multi‑tenant backend services for assignment, data pipelines, and metrics in the experimentation domain
• Own gRPC/protobuf APIs and data contracts: evolve schemas safely, plan deprecations and migrations, and protect compatibility
• Drive reliability: define SLOs and error budgets, improve p95/p99 latency, reduce alert noise, and lead on‑call incident response and postmortems
• Level‑up observability (tracing/metrics/logging) and performance; profile and optimize for cost and scale in GCP
• Collaborate with the Customer Success team to transform recurring issues into runbooks, tooling, SDK/docs fixes, and productizable improvements
• Contribute primarily on the backend (Java/JVM, gRPC) while collaborating across the stack and with data warehousing integrations
• Write RFCs and drive impact in an asynchronous and distributed team proactively

Who You Are

• You are a backend engineer with strong Java/JVM fundamentals and experience building and operating distributed systems at scale.
• You are comfortable owning production: on-call rotations, incident triage, debugging across services, and driving durable fixes.
• You are product-minded and pragmatic, with a bias to ship incrementally under ambiguity.
• You are comfortable with lightweight process, high trust, and clear written alignment.
• You are experienced with API/SDK design (gRPC/protobuf), versioning strategies, and developer-experience trade-offs.
• You are fluent with modern cloud/platform tooling (preferably GCP: GKE, Pub/Sub, managed storage).
• You have excellent written communication and async collaboration skills, and you are comfortable influencing across org boundaries.
• You have an experimentation background, or you show strong interest and ability to learn quickly.
• You may have bonus experience with data warehousing beyond BigQuery, or with experimentation/feature flag vendors.

Where You'll Be

• This role is based in London
• We offer you the flexibility to work where you work best! There will be some in person meetings, but still allows for flexibility to work from home