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Portfolio Jobs

Looking for your next role? Take a look at these exciting jobs at Sapphire Ventures’ portfolio companies. Our Talent team is passionate about connecting you to your dream job!

Senior AI Platform Engineer, Real Time Systems

PubNub

PubNub

Software Engineering, Data Science
Poland · Remote
Posted on Dec 18, 2025

About PubNub

PubNub powers the world’s most engaging real-time experiences—chat, live updates, and interactive applications—for over 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. Backed by $130M in funding, we’re shaping the future of how the world connects.

We’re now building something new: an intelligence layer that lets developers weave large language models (LLMs) and deep-learning pipelines directly into high-speed streams. We believe AI should be as real-time as the data it reasons about, and we’re hiring founding engineers to make that vision real.

About the Role

We are looking for a Senior AI Engineer to design and operate AI systems that run in real time and at high scale. You will join a focused AI team responsible for building production-grade AI features and shared infrastructure that enables other engineering teams to deploy AI safely and efficiently. This role is remote-first within Poland, with the option to work from our Katowice office if you prefer.

Responsibilities

  • Design, build, and maintain AI-powered services integrated into PubNub’s platform
  • Architect low-latency ML and LLM pipelines processing millions of messages per minute
  • Build internal frameworks, APIs, and tooling for AI feature adoption
  • Train, fine-tune, and operate models in production
  • Develop and maintain infrastructure for running LLMs at scale
  • Extend existing backend and client systems to support AI features
  • Collaborate with product and engineering teams on system design and trade-offs
  • Improve developer experience through clean APIs, SDKs, and documentation

About you

Must Have

  • 5+ years of software engineering experience
  • 1+ year of hands-on experience with AI/ML systems in production
  • Experience shipping customer-facing AI features
  • Experience deploying and scaling LLMs in production
  • Experience working with high-throughput systems (millions of messages/minute)
  • Strong knowledge of TypeScript, Python, or Rust
  • Solid system design and backend development skills
  • Regular use of AI-assisted development tools (Copilot, Cursor, Claude, etc.)
  • Fluent English

Nice to Have

  • Real-time or streaming systems (Kafka, Kinesis, WebSockets)
  • Developer platforms, SDKs, or internal tooling
  • Cloud AI platforms (AWS Bedrock, Azure OpenAI, Vertex AI)
  • Docker, Kubernetes, infrastructure as code
  • Model serving frameworks (TorchServe, MLflow, TensorRT)
  • Vector databases and embedding-based systems

Why Join PubNub

  • Build a greenfield intelligence platform at internet scale
  • Ship features that land directly in customer-facing products across healthcare, fintech, gaming, and streamingAbout the Role
  • High ownership and influence over technical decisions
  • Remote-first setup within Poland
  • Competitive B2B compensation ranging between PLN26,000 - PLN32,000 per month
  • Open paid time off
  • Stock options
  • Optional office in central Katowice

If you’re excited to make AI real-time, we’d love to hear from you.