Founding Engineer

 

Description:

 

Full time, based in London with hybrid working. You'll work directly with the CTO across the entire Prysm stack: frontend, backend, and the agent layer that is the heart of the product. This is a genuine generalist role with an AI centre of gravity. In a typical month you might:

 

- Improve the document-parsing pipeline so messy, inconsistent broker PDFs come through clean, structured, and queryable.

 

- Push the frontier of what agents can do in financial analysis: building the modelling agents that project cash flows, size debt, and run sensitivities as part of how a deal gets underwritten.

 

- Build the eval system that scores agent output against analyst-reviewed ground truth.

 

- Optimise an agent: tune prompts, restructure the lead/subagent orchestration, improve the extraction flows, and measure the quality difference.

 

You won't be siloed. The whole point of this hire is breadth: someone who can own a feature from database migration to frontend rendering.

 

The stack you'll work in

 

We build with a modern TypeScript-and-Python stack and lean on best-in-class tools for the AI layer. Specifics will shift as the product and the ecosystem evolve; what matters is being comfortable across the whole thing:

 

- Frontend: A modern Next.js/React/TypeScript web app

 

- Backend: Python + FastAPI

 

- AI / Agents: LLM agent orchestration with Pydantic AI and MCP; lead-agent + subagent patterns and tool design

 

- Data & retrieval: PostgreSQL with vector and full-text search, embeddings, and reranking powering RAG over documents

 

- Document AI: LLM pipelines that turn messy PDFs into structured, queryable content

 

What we're looking for

 

5-6+ years of professional engineering experience. We care far more about range, judgement, and trajectory than years on a CV.

 

Must-haves:

 

- AI agent expertise. Hands-on experience with agentic AI harnesses, e.g. LangChain or Pydantic AI, and building, optimising and orchestrating agents.

 

- Strong Python. You write clean, well-structured, production Python and are comfortable in an async, API-driven codebase.

 

- Full-stack confidence. You can hold your own on the frontend in TypeScript/React, and you're happy owning a feature across the whole stack.

 

- A fast, fearless learner. New framework, new SDK, new corner of the system: you pick it up and ship. Our stack will keep evolving and we need someone who's energised by that, not unsettled by it.

 

- Genuinely excited by AI. This isn't a buzzword for you. You're inspired by what agentic AI can do and you want to spend your days building it.

 

- AI-native in how you build. Our development workflow is deeply agentic. You live in tools like Claude Code, Codex, or Cursor (whatever your weapon of choice) and you've built real fluency in driving them well