Founding Product Engineer

present of AI; San Francisco (CA); On-site; USD 100,000 - 140,000; Full time

Job summary

Arceus is seeking a hands-on builder in San Francisco to take features from idea to production across the full stack. You will work alongside attorneys and AI engineers to turn legal workflows into dependable product tools, applying real-world trade-offs to keep quality high.

As part of the AI era, you will build with LLMs, ship end-to-end features, and own delivery from concept to deployment in a fast-paced environment that blends law and software.

Qualifications

• Early in career software engineer who has shipped real software.
• Able to take features from idea to production in a full-stack context.
• Works closely with attorneys and AI engineers to encode workflows into software.

Responsibilities

• Translate legal workflows into dependable product features.
• Ship features from concept through production in collaboration with attorneys and AI engineers.
• Balance practical trade-offs with quality to deliver reliable tools.

Skills

Full stack TS/React

LLMs

End-to-end ownership

Fast delivery

Tools

TypeScript

React

Job description

This is a hands on builder role for someone early in their career who can take features from idea to production across the whole stack. A strong candidate has shipped real software, likely at a startup or through their own company, and can make practical trade offs while keeping quality high. The work pairs closely with attorneys and AI engineers to turn legal workflows into dependable product features.

How it fits the AI era

The product turns legal judgment into software, so the engineer works alongside attorneys and AI engineers to encode review playbooks and workflows into reliable tools. AI handles parts of contract review and drafting, while the human side stays in product judgment, architecture choices, and owning what ships. The role sits where AI capability meets real user experience.

How it builds AI experience

Building with LLMs is expected, whether from a job or personal projects, and this role deepens that by applying AI to contract review and drafting inside a law firm. A candidate can prepare by shipping something that uses language models in a real workflow and by learning how legal review steps get structured. Working next to attorneys and AI engineers gives direct exposure to how AI agents and the firm's own software handle contracts.

Worth showing

• Full stack TypeScript React
• Built with LLMs
• Owned features end to end
• Fast pragmatic execution

This is our own read, written from the employer's posting and the company's Spotlight. The employer's posting is the source of truth for the role.

About Arceus

Arceus is a law firm that pairs licensed U.S. attorneys with AI agents and its own CounselOS software to review, draft, and negotiate commercial contracts, per the company.