Senior Software Engineer in London - Oscar Technology

Senior Software Engineer (Backend / Full-Stack, AI-Native)

About Us
We're rethinking enterprise integration for developers and AI agents with a semantic layer: describe the data you need, and the platform gets it - fast, deterministic, secure, self-repairing, auditable, scalable. Already live with banks and financial institutions, and hiring to build the product further. You'll work across our data integration platform and our open-source schema language and ecosystem.

What You'll Work On
Mostly Kotlin backend, but everyone touches the full stack: the integration platform (streaming pipelines, query execution, API composition, schema resolution, running in production at real financial institutions); our open-source schema language (compiler, type system, query engine, no prior compiler experience needed); our AI agent built on Spring AI (greenfield work orchestrating integrations autonomously); and the frontend (mainly Angular, some React, no specialism required).

What We're Looking For
Kotlin, or strong modern Java 17+ with a willingness to learn; reactive streams experience (Flux, Mono, coroutines, backpressure); schema/type thinking (OpenAPI, Avro, Protobuf, or similar); event-driven architecture awareness (Kafka or RabbitMQ a plus); strong testing habits; clean, pragmatic code; curiosity and adaptability; full-stack willingness (Angular, React, Vue, or similar); active use of AI-assisted coding tools; strong written English for a distributed, mostly async team; and 5+ years of professional experience shipping production systems.

How You'll Need to Work
Autonomously, with context and support rather than daily assigned tickets; collaboratively, staying constructive when things break or priorities shift; with genuine customer empathy; openly, sharing your work internally and externally; and at startup pace, where some days are scrappy.

Nice to Have
Kafka or RabbitMQ experience, Angular/TypeScript specifically, deep Kotlin/JVM ecosystem knowledge, compiler or query engine experience, Spring AI or LLM agent experience, financial services background, or a blog/talks/open-source contributions.

What We Offer
GBP salary plus early-stage equity, remote-first work (UK-friendly timezones) with occasional onsite office days roughly monthly, a budget for conferences and learning, and a hardware and tooling budget.

Oscar Associates (UK) Limited is acting as an Employment Agency in relation to this vacancy.

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