Founding Engineer
The basics £80K - £120K base salary + founding equity London (Hoxton) | 5 days/week in-office
You'll architect, ship and own the agentic AI brain that powers Letty, from day 1 to international scale.
✨ 6 reasons this role is remarkable
- Build the brain. You'll own the core AI agent infrastructure. Telephony, LLM orchestration, RAG pipelines, and the event-driven architecture that ties it all together.
- Be a founding engineer at an AI company rewriting a trillion-dollar industry. Property still runs on scribbles, spreadsheets, and "sorry, we missed your call."
- Ownership from day one. Make product and technical decisions independently. Scope features, ship them, own them in production.
- Massive market, and we're just getting started. Agency operations is the wedge. The long-term play is owning both sides of the transaction. Matching tenants to properties, building the platform that represents landlords/seller and buyers/tenants at the same time.
- Work on something that matters. We're changing how millions of people rent, buy, and live. This isn't another SaaS dashboard.
- A role that grows with the company. Shape the technical direction as we scale internationally.
👋 What are we building?
The problem
Property is one of the most important parts of people's lives, and the industry serving it is stuck decades behind. Agencies are fragmented, compliance-heavy, labour-intensive and deeply inefficient.
Our vision
Letty will be the last-ever real estate agent. A series of fully automated, agentic-AI-driven employees that negotiate rents, dispatch tradespeople, reconcile ledgers, and manage the entire tenant experience while we sleep.
But agency operations is just the entry point. The real prize is what sits on top: an intelligent matching layer that connects the right tenants to the right properties, helps chains come together, and ultimately sits on both sides of the transaction.
We're stitching together matchmaking, compliance, payments, maintenance and tenant experience into one seamless platform.
We're raised from top-tier VCs, backed by Entrepreneurs First, and live in agencies across the UK with early US traction. If you want to be in the driver's seat rebuilding how our entire society lives, this is your chance.
🛠️ What you'll do
Build and scale the AI agent backend. Architect and own the core Python backend powering our AI agents.
Own the AI infrastructure. Build the telephony and voice layer, LLM orchestration, and RAG pipelines Ship rock-solid backend systems. Build robust API integrations with CRMs and property management systems.
Design for scale. Build API-first, event-driven architectures that handle real-time workloads.
Jump across the stack. Contribute to frontend work (TypeScript, React, Next.js) when needed.
🎯 You'll be a great fit if
🐍 You have 3+ years of Python with strong FastAPI experience, plus solid backend fundamentals. Postgres, Redis, async processing, queuing systems (Celery, RabbitMQ/SQS), and CI/CD pipelines.
🤖 You have 2+ years building and shipping AI agents and LLM-powered systems in production, including end-to-end orchestration (LangGraph or similar).
🔍 You have strong RAG experience. Structuring unstructured data, making it queryable by LLMs, hands-on with vector databases (Pinecone, pgvector, or similar).
🏗️ You've designed and deployed API-first, event-driven architectures. You intuitively know how to build systems that scale.
🔭 You have experience with observability and debugging in production. LangSmith, Datadog, Sentry, and similar.
🧠 You've demonstrated ownership of system design and technical decision-making. You've built entire backend systems from scratch.
💬 You're a strong communicator and fast thinker and speaker.
⭐ Nice-to-haves
🎙️ Voice AI and real-time communication (LiveKit, Twilio SIP, WebRTC).
🔊 Experience with STT/TTS pipelines (Deepgram, ElevenLabs, Cartesia, or similar).
📱 WhatsApp Business API, Twilio and similar messaging platform integrations.
🚀 Previous founding engineer or CTO experience.
🚫 This role isn't for you if
🖥️ You want a predictable 9-to-5. We're building fast and the work is intense. We respect life outside of work, but we do what it takes to win.
🧱 You need structure handed to you. You'll be making product and technical decisions independently, often as the sole engineer on a feature from scoping through to production.
📋 You're an architect, not a builder. If your experience is designing systems on whiteboards rather than shipping and owning them in production, this isn't the fit.
🎁 And there's also the perks...
We're building a high-performance environment. You'll work hard, and we want to clear your plate so you can perform at your very best.
🏥 Private health insurance
🚗 Uber home if you're working late
🍲 Doordash dinners in the office
🧽 Fortnightly home clean
💻 Brand new MacBook
📌 How do I join the journey?
Apply and tell us why you're interested.
Intro Call. A 30-min chat about your ambitions and our biggest technical challenges.
Work Trial. A paid working session with our founding team.
Offer. And you'll join us on the journey.