Senior Backend Engineer, Customer Data Platform

Piano Overview Piano’s Digital Experience Cloud empowers organizations to understand and influence customer behavior. By unifying customer data, analyzing behavior metrics and creating personalized customer journeys, Piano helps brands launch campaigns and products faster, strengthen customer engagement and drive personalization at scale from a single platform. Headquartered in Philadelphia with offices across the Americas, Europe and Asia Pacific, Piano serves a global client base, including Air France, the BBC, CBS, Kirin Holdings, Jaguar Land Rover and more. Piano has been recognized as one of the fastest-growing, most innovative technology companies in the world by World Economic Forum, Red Herring, Inc. and Deloitte. For more information, visit piano.io. About the Role You will join the Customer Data Platform team as a senior individual contributor, working from our Warsaw office. The team is headquartered in Kyiv. CDP spans many mostly Node.js/TypeScript services: a high-throughput event pipeline, a query and search layer over Elasticsearch, scheduled background processing, and sandboxed execution of customer-authored logic. This team is AI-first. Claude Code is the primary development environment and hand-written code is being phased out as the default. Our repositories carry CLAUDE.md context, .claude/ agents, commands and skills, and internal MCP servers. Daily experience working this way is a requirement; agent-written code carries the same accountability as any other. About a third of what we merge is platform custodianship — dependency and TypeScript upgrades, static analysis, CVE migrations, CI, legacy teardown. Much of it suits agents well, and that share is not optional. What You'll Do Deliver through Claude Code and raise the team's bar on it: better context, better agent tooling, better evaluation of agent output.Own event-pipeline services under load spikes and pathological traffic: backpressure, load shedding, circuit breakers, retries, dead lettering.Own the Elasticsearch query and search layer: deep pagination, behavior under memory and rate limits.Own sandboxed execution of customer logic, and integrations with other Piano products and third-party systems, including their API contracts.Drive integration work across team boundaries: negotiate technical contracts with other Piano engineering teams and coordinate rollouts spanning services you don't own.Scope epics and trade-offs with technical, product and business counterparts, and turn the outcome into decision records other teams build against.Review teammates' work with depth scaled to risk, and test determinism as the bar.Run production changes end to end through Helm and FluxCD GitOps.Take a recurring on-duty rotation: alerts, P1/P2 triage, hotfixes, and root cause communicated to enterprise customers. What We're Looking For Must-have Daily, fluent Claude Code practice on production code, and sharp judgment about where an agent can be trusted and where it must not be.Strong Node.js and TypeScript: ESM, strict tsconfig, Jest/Mocha.Deep Elasticsearch 8.x: mappings, reindex, sort and range semantics, deep pagination, backpressure.Kafka at scale: partitioning, consumer concurrency and lag, dead-letter handling, topic lifecycle.Production ownership as a habit: on-call, evidence-backed root cause, Datadog instrumentation, toggle-gated rollouts, and profiling-driven performance work.PostgreSQL with an ORM: migrations, indexing, transaction semantics.Willingness to own Kubernetes, Helm, GitOps and GitLab CI, plus dependency and CVE triage.Clear technical English and the ability to hold a technical position with product and business stakeholders.Nice-to-have Building MCP servers, agent skills, or other internal tooling that makes coding agents more effective.Efficient JavaScript execution: V8 isolates, timeouts, resource limits.ClickHouse, Aerospike, ArangoDB, Redis.gRPC, Testcontainers, WireMock; de-flaking time-dependent tests.Large-repository tooling such as Rush and pnpm workspaces.High-volume, multi-tenant data platforms.Maintenance-level Java on an existing end-to-end test suite. Why Piano Real ownership of systems global media brands depend on, from design through production.Real influence over the tech stack and the freedom to choose your tools.Generous token usage budgets, with a focus on getting value from coding agents.Flexible working hours, competitive compensation and benefits, and a laptop of your choice. Piano is an equal opportunity employer. Applicants must be authorized to work in Poland without sponsorship from Piano.