Senior Software Engineer at Katapult Labs

HYBRID ROLE: 85% REMOTE, BUT REQUIRES 3 NIGHTS ON-SITE IN MIAMI OR NYC EVERY MONTH. THIS IS NOT A REMOTE POSITION. CANDIDATES MUST LIVE IN THESE LOCATIONS, HAVE VALID WORK AUTHORIZATION, AND BE FULLY BILINGUAL (ENGLISH/SPANISH). PLEASE APPLY ONLY IF YOU MEET THESE SPECIFIC CRITERIA. ABOUT THE COMPANY Our partner is a stealth-stage legal technology company applying AI to plaintiff-side litigation at institutional scale, with eyes toward reinventing the way law is practiced end-to-end. They operate at the intersection of special situations litigation and litigation finance building infrastructure that doesn't yet exist in the legal industry. They raised a seed round that was 75% oversubscribed in February 2026, and they're building the team that will define how this company grows. Their engineering culture is small, deliberate, and high-stakes. This isn't a place where you hand off tickets and wait for feedback. It's a place where precision matters, where the domain has real consequences, and where the expectation is that you think in systems, not features. THE ROLE We're looking for a Founding Builder; the next person to join the core team. This isn't a job description for an engineer slot. It's an invitation for someone who has already proven they belong in the top 1% of their craft and wants to build something that matters. You'll work across the full stack — backend-first, owning architecture end-to-end, and with taste for elegant and convenient UX/UI while collaborating closely with a product-leaning counterpart. You'll design systems around AI, not just use it. LLM orchestration, agentic workflows, MCP integrations. The domain is regulated and high-precision. Prior exposure to legal tech, compliance-adjacent data pipelines, or enterprise SaaS in a domain with real stakes is a strong signal. You understand why a wrong output has consequences and you build accordingly. WHAT WE'RE LOOKING FOR You have Software engineering depth with a backend-first instinct. You're comfortable owning complex platforms and products end-to-end without hand-holding, and you've shipped production-grade systems that you'd stand behind today. You're AI-native by default. You design systems with and for AI, not around it. You've built with LLMs in production not as a feature, but as infrastructure. You operate at high autonomy, low maintenance, low ego. You communicate precisely, flag blockers early, ship in fast-moving environments, and don't need structure imposed from above. You've worked in a domain where precision matters: legal, compliance, healthcare, fintech. You know what it means to be wrong in a regulated context. TECH STACK - Frontend: Next.js 16, React 19, TypeScript 5.9, Tailwind CSS 4, shadcn/ui, Radix UI, Recharts, MapLibre GL, Framer Motion, Lucide React - AI: Anthropic Claude API (SDK), Server-Sent Events streaming, custom agentic tool system, dynamic skill loading from S3 - Backend: Next.js API routes, Auth.js (NextAuth v5), Drizzle ORM, PostgreSQL, DuckDB, S3-backed Parquet files - Data Pipeline: Python 3.13, Hive-partitioned Parquet on S3, DuckDB analytical engine LOGISTICS - Based in New York or Miami preferred; exceptional candidates in other locations considered - Person fluent in English and Spanish - 85% remote with monthly in-person meetings in New York and Miami (3 nights) - Monster equity: 0.20%–0.99% of the business as of May 2026 — meaningful, early-stage ownership in a well-funded company - 4-round interview process: founder screen (25 min) → blind work sample → half-day panel (ethics + adversarial assessments) → social event with the team - Founding Builder — New York / Miami