Senior Backend Engineer (AI / LLM Systems)

About PubNub PubNub 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 Do Ship AI-powered features into production Integrate 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 scale Design 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 teams Build 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 & Communication Work 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 office If 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.