Senior Backend Engineer (AI / LLM Systems)

About PubNubPubNub is a San Francisco–based product company powering real-time experiences including chat, live updates, and interactive applications for 2,000+ companies including Verizon, Autodesk, Zillow, and Dropbox.Our global data network processes trillions of messages each month with sub-100 ms latency across 15+ data centers worldwide.We’re building an AI capability layer that helps developers add AI features to real-time streams such as classification, summarization, routing, enrichment, and automation, without breaking latency, reliability, or trust.What You’ll DoShip AI-powered features into productionIntegrate LLM inference, build evaluation and observability tooling, and own the full lifecycle of AI services — from quality metrics and tracing to cost and reliability.You’ll work with providers like OpenAI, AWS Bedrock, Azure, or open-source models and deliver features used by real customers.Build & operate AI services at scaleDesign low-latency inference pipelines for high-throughput message streams.Implement model routing, prompt and retrieval patterns (RAG), caching, batching, and fallbacks.You’ll solve real-world constraints around latency, scale, and cost.Enable other teamsBuild internal frameworks, APIs/SDKs, and tooling so other teams can ship AI features safely and consistently.Partner with product and engineering on trade-offs between latency, cost, accuracy, and privacy.Clear documentation and great developer experience matter here.Tech & CommunicationWork mainly with TypeScript, Python, or Rust (and be open to learning the others).Use modern AI-assisted tools (Copilot, Cursor, Claude, etc.).Communicate clearly in English.How we Work• Long-term B2B collaboration (full-time engagement)• Competitive monthly compensation: 26,000 – 35,000 PLN + VAT• Remote-first within Poland• Flexible time management focused on outcomes• Access to modern tools and infrastructure required to perform the role effectively• Equity participation opportunity• Optional access to our centrally located Katowice officeIf this sounds like the kind of systems challenge you enjoy, apply and include a short note about a production AI feature you’ve shipped.We review every application personally.