Senior Fullstack Engineer, Product

The role

This is a hands-on individual contributor role. You will build the chat experience for diners and own the agent runtime end to end.

What you will do

• Build the chat experience diners talk to every day.
• Own the agent runtime end to end.
• Ship new tools the model can call, and the tests that pin their behavior.
• Make answer quality measurable: evals, tracing, and real user feedback.
• Improve retrieval so the agent recommends the right place.
• Take the product from answering questions to completing tasks.
• Keep turns fast, cheap, and reliable on mobile networks.
• Get work in front of real diners fast, with product and design.

Required qualifications

• 5+ years shipping production software, owning features end to end.
• Able to debug across the stack: a streaming client, application code, SQL, and the boundaries between services.
• Real depth with LLM application development: tool calling, context management, retrieval, streaming.
• Strong React and TypeScript, fluency in Python, and willingness to work in Kotlin/Spring when the answer lives on the platform side.
• Solid Postgres and data modeling instincts, including a feel for what makes retrieval good or bad.
• Taste in evaluation: you know the difference between fixing a failing eval and gaming one.
• Product judgment about what makes an agent feel trustworthy, fast, and worth coming back to.
• Comfort with ambiguity and high ownership on a small team.
• You use current models seriously and have your own ideas about how agent systems should work.

Nice to have

• Agent evals and LLM observability tooling (Langfuse, Braintrust, LangSmith).
• Vector and geospatial search in Postgres (pgvector, PostGIS).
• Shipping AI into a native mobile surface: streaming, cold starts, bad networks.
• Frontier model APIs: tool use, prompt caching, extended thinking.
• Restaurants, hospitality, travel, or another domain where recommendations carry real-world consequences.
• Datadog, Amplitude, LaunchDarkly, AWS, or Terraform.

About the company

Blackbird Labs is a loyalty and payments platform establishing meaningful connections between the world’s best restaurants and their customers. It offers a customizable loyalty programming platform for restaurants and a consumer app.