Senior Fullstack Engineer, Product
Blackbird Labs Inc · New York
About this role
**ABOUT BLACKBIRD** Blackbird Labs is a loyalty and payments platform connecting the world’s best restaurants with their customers. We offer a fully customizable loyalty programming platform for restaurants and a consumer app that makes every guest feel like a VIP—backed by investors including Union Square Ventures, a16z, Amex Ventures, and Variant Fund. **ABOUT THE ROLE** We’re looking for a product-minded **Senior Fullstack Engineer** to own building our chat/agent experience end to end. This is a hands-on IC role—everyone builds and ships. Problems span the stack (e.g., rendering bugs, prompt regressions, retrieval plan issues, backend endpoints), and you’ll follow them wherever they go. **RESPONSIBILITIES** - Build the chat experience diners talk to every day - Own the agent runtime end to end - Ship new tools the model can call, along with 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 quickly with product and design **REQUIREMENTS** - 5+ years shipping production software, owning features end to end - Ability to debug across the stack: streaming client, application code, SQL, and service boundaries - Strong depth in LLM application development (tool calling, context management, retrieval, streaming) - Strong React and TypeScript; fluency in Python; willingness to work in Kotlin/Spring when needed - Solid Postgres and data modeling instincts, including what makes retrieval good vs. bad - Strong evaluation taste (know the difference between fixing failing evals vs. gaming them) - Product judgment for what makes an agent feel trustworthy, fast, and worth returning to - Comfort with ambiguity and high ownership on a small team - Serious use of current models with your own ideas about how agent systems should work **NICE TO HAVES** - Agent evals and LLM observability tooling (Langfuse, Braintrust, LangSmith) - Vector and geospatial search in Postgres (pgvector, PostGIS) - Shipping AI into native mobile surfaces (streaming, cold starts, bad networks) - Frontier model APIs (tool use, prompt caching, extended thinking) - Domain experience in restaurants/hospitality/travel or other recommendation-heavy areas - Datadog, Amplitude, LaunchDarkly, AWS, Terraform **PAY TRANSPARENCY & BENEFITS** Target annual salary range: **$180,000–$220,000 USD** (equity not included). **EQUAL OPPORTUNITY** Blackbird Labs is an Equal Opportunity Employer committed to diversity. All qualified applicants will receive consideration without regard to protected characteristics. Blackbird also participates in E-Verify. *If you’re excited about building trustworthy, fast, product-grade agent experiences for real diners, we’d love to hear from you.*
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