Join as the third founding engineer at a London Bridge-based startup replacing manual spreadsheets with agentic AI. You will build systems that extract billing logic from complex contracts to automate invoicing and collections. This is a high-impact role for a builder ready to ship fast in an intense, in-office environment.
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London, United Kingdom£100k-£130k + 0.6-0.8% Equity
Founding Engineer at venture-backed AI agent startup
Are you a Python expert ready to build the future of finance? This venture-backed startup at London Bridge is looking for their third Founding Engineer to automate complex accounts receivable using agentic AI. You'll move beyond simple prompts to build sophisticated systems with LangGraph and Temporal, replacing manual spreadsheets with autonomous billing agents. If you thrive in high-intensity environments and want a significant equity stake in a fast-growing company, this is your chance to own a major piece of the product from day one.
Overview
Role overview
Company
Spinal
Venture-backed AI agent startup automating accounts receivable for modern finance teams
Responsibilities
What you will do
- Architect and deploy agentic AI systems that process unstructured legal documents and contracts into structured, deterministic billing data.
- Build and maintain mission-critical backend services using Python, Pydantic, and Postgres to manage automated collections and revenue recognition.
- Take full ownership of product features from ideation to production, shipping daily and participating in weekly demo sessions to drive rapid iteration.
Candidate profile
Who this is a fit for
- 3-5 years of professional Python backend experience with a proven track record of shipping complex systems in production environments.
- Hands-on expertise with agentic AI frameworks like LangChain or LangGraph, specifically focused on turning unstructured data into structured outputs.
- A founding mindset demonstrated through previous experience as an early employee, founder, or through high-achievement in competitive domains like academics or sports.
What makes it remarkable
Why this role is remarkable
- Significant equity stake (0.6-0.8%) in an early-stage company, offering true ownership and the chance to shape the technical foundation from the ground up.
- Work at the cutting edge of agentic AI using LangGraph and Temporal to solve complex, real-world financial orchestration problems for modern companies.
- High-density talent environment working directly with a CTO and CEO to move from zero to one in a fast-paced, high-iteration office setting.
Jack & Jill
How Jack & Jill work together
I get to know what you’re great at, then find roles you’d never find yourself.Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.
I recruit from Jack’s network and make the intro when I spot a great match.And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.
Meet Jack
Jack gets to know what you're great at and what you want next, then searches 14 million jobs daily and introduces you directly to hiring managers.
How does this work?
Jack's an AI agent for job searching and career coaching. He works for you.
Jill is the AI recruiter working for the company. She recruits from Jack's network.
If it's a match and the company wants to meet you, they'll make the intro. In the meantime, if you'd like, Jack will send you excellent alternatives.
Jack