Founding Engineer (Full Stack) – w / Equity

TEN-XER; England; On-site; GBP 50,000 - 70,000; Full time

Job summary

A leading legal tech company in the United Kingdom is seeking a skilled Full-Stack Developer to build innovative features for their AI platform. This role involves designing and implementing solutions that influence the resolution of crucial legal disputes. Ideal candidates will possess over 3 years of full-stack development experience, with strong skills in Python and TypeScript. You'll have equity, direct access to users, and the chance to redefine AI tools for law. A background in legal tech is a bonus.

Benefits

Equity options

Direct access to founders and users

Impactful role in legal tech

Qualifications

• 3+ years of experience in building and shipping web applications.
• Strong backend experience with Python or similar technologies.
• Frontend experience in TypeScript frameworks like Next.js or React.

Responsibilities

• Build core product features spanning cloud infrastructure and UX.
• Work with litigators to integrate Crimson into their workflows.
• Architect and scale document processing pipelines.

Skills

Building production web applications full-stack

Backend development with Python

PostgreSQL

Cloud infrastructure (Azure preferred)

Frontend development with TypeScript frameworks (Next.js or React)

Designing data pipelines

Working with LLMs and applied AI

Excellent communication skills

Job description

About Ten-Xer

At Ten-Xer, we match people to roles where they can actually build and grow. We partner with startups that want operators, not passengers, and help them hire talent who move fast and deliver outcomes.

About Crimson

Crimson is an AI productivity platform built for litigators. Litigation teams use Crimson to analyze case files, answer case-specific questions and draft documents tailored to each dispute. By automating manual workflows across the life cycle of a case, Crimson helps lawyers find key evidence faster, streamline case management and save 10+ hours per week on common litigation tasks.

Crimson is a small, high-ownership team of three co-founders building a category-defining AI platform for high‑stakes litigation. They work with major UK and US law firms on highly sensitive case files. The culture is product-driven and security‑obsessed: engineers talk directly to users, own features end‑to‑end, and care deeply about accuracy, reliability and speed. YC‑backed and focused on shipping quickly while learning from demanding users.

What You’ll Do

• Build core product features across the stack from cloud infrastructure to prompting to UX, including Python backend, Next.js with TypeScript frontend, PostgreSQL, and Azure‑hosted LLM workloads with CI / CD pipelines via GitHub Actions and IaC such as Bicep
• Work directly with litigators and knowledge workers to understand how lawyers work, what they need, and how Crimson can fit into their workflows
• Architect and scale document ingestion and processing pipelines to power fast, accurate search, summarization and data extraction over large volumes of legal documents
• Design and implement intelligent, multi‑step agent workflows that autonomously handle complex legal tasks from surfacing key testimony to generating fact chronologies and spotting inconsistencies in filings
• Design and ship intuitive, AI‑native user experiences tailored to litigation workflows in partnership with founders and early customers
• Improve system performance, stability and observability as the platform scales to more cases, larger datasets and additional firms
• Shape engineering culture and team standards from best practices and code quality to interviewing, hiring, and mentoring future engineers

What You Bring

• 3+ years building and shipping production web applications full‑stack, ideally in startups or small, high‑ownership teams
• Strong backend experience with Python or similar, PostgreSQL, and cloud infrastructure with Azure preferred but AWS or GCP also relevant
• Frontend experience with modern TypeScript frameworks like Next.js or React, and an eye for building clean, intuitive product experiences
• Experience designing and operating data pipelines or distributed systems that handle large volumes of text or documents
• Comfort working with LLMs and applied AI including prompting, integrating model APIs, and thinking carefully about correctness, reliability and UX for AI‑powered features
• Excellent product judgment, communication skills and attention to detail with comfort talking to demanding users and turning their feedback into shipped features
• High agency and bias for shipping with a preference for owning problems end‑to‑end and seeing your work used in real cases
• Bonus: interest or background in legal tech, disputes, or working with professional services users

Why this role matters

You’ll be building tools that change how some of the most critical legal disputes get resolved. Your work will directly impact case outcomes, billable efficiency and how litigation teams operate under pressure. You’ll have equity, direct access to founders and users, and the chance to define what AI tooling for law should actually look like.