Senior/Staff Software Engineer

Senior / Staff Software Engineer FluxCap | New York City or Washington, DC | Hybrid | Full-time Build the product and systems lawyers can trust with a complex case. About FluxCap Strong cases should get their day in court. FluxCap helps lawyers connect the law, evidence, and strategy of a case so they can take on bigger opponents and win on the merits, regardless of the size of their team. We’re starting with antitrust. Founded by Jonathan Kanter and Doha Mekki, former leaders of the Justice Department’s Antitrust Division, FluxCap brings together former DOJ lawyers and engineers from Palantir and Meta. We’re backed by Y Combinator, Bloomberg Beta, and other investors. The role You’ll work directly with the CTO, founders, and legal engineers to build software around how litigators develop a case. You’ll own features across the stack, from the interface a lawyer uses to the data model and AI workflows behind it. A single document might support one legal argument and undermine another. You’ll build systems that preserve those distinctions, show the evidence behind a conclusion, and incorporate a lawyer’s corrections as the case develops. This is a hands-on individual contributor role. You’ll write production code, make architectural decisions, and stay responsible for how your work performs after it ships. Our stack includes React, Next.js, TypeScript, and Postgres with pgvector. Senior engineers own a major product area. Staff engineers also lead technical decisions across product areas and help the team carry them through implementation. Both roles involve writing production code. What you’ll do

• Own major features from the first design through launch and ongoing use.
• Design data models that connect claims to the facts and evidence needed to prove them. Preserve sources and allow lawyers to record competing interpretations.
• Build workflows that extract people, events, and timelines from documents and help lawyers find gaps in the evidence.
• Build evaluations and review tools that catch AI errors and incorporate attorney corrections without exposing information from other cases.
• Make tradeoffs around reliability, performance, and cost. Review code and help other engineers work through technical decisions.

A problem you might work on A lawyer corrects how the system interprets one passage in a document. Later, hundreds of thousands of new documents arrive. How should the software preserve that correction, find new evidence that matters, and explain what changed without reprocessing the entire case? What you’ll bring

• 5+ years shipping production software, including responsibility for designing, building, and maintaining a significant product or system.
• Strong React, TypeScript, and Next.js skills. You can build a usable interface and follow the work through the backend and database.
• Experience building and operating LLM-powered features, including retrieval or agent workflows.
• Experience making architectural decisions under constraints such as deadlines, cost, or performance.
• Ability to work through unfamiliar problems with lawyers, explain technical choices, and give useful feedback to other engineers.

Helpful experience

• Vector search, document processing, or background jobs.

Legal experience isn’t required. Curiosity about the domain and care for sensitive information are essential. Compensation and benefits

• Annual base salary: $170,000–$220,000 + competitive equity
• Medical, dental, and vision insurance
• 401(k) with an employer match
• Company-paid life insurance and short-term disability
• Learning and professional development budget

This is a hybrid role based in New York City or Washington, DC. Candidates willing to relocate are welcome. Interview process

• Introductory conversation
• Virtual technical interview covering system design and AI-assisted coding
• One-day work trial in NYC
• Founder conversation
• References

You must be authorized to work in the United States. We are not currently able to sponsor visas.