Founding Engineer

• Build and evolve the interfaces agency teams use to monitor AI conversations, intervene when needed, configure agent behaviour and understand what’s happening across their business.
• Own onboarding flows, authentication, permissions, admin controls, billing and the day-to-day product surfaces customers live in.
• Build dashboards and data-heavy interfaces that make large amounts of structured and unstructured information genuinely usable.
• Design AI-native interfaces with clear status, editable outputs, graceful fallbacks and human-in-the-loop workflows.

Build the systems behind them.

• Work across our Next.js / TypeScript application and Python / FastAPI services.
• Build and evolve LLM-powered workflows, agents, RAG pipelines and data layers.
• Work with streaming responses, structured outputs, tool calling and agent orchestration.
• Integrate with CRM systems, telephony providers, WhatsApp, SMS, email and the rest of the software estate agencies already use.
• Work with PostgreSQL, Redis, vector databases and other infrastructure required to make the product reliable at scale.

Own what you ship.

• Take features from customer problem to architecture to production.
• Debug production issues across frontend, backend and LLM systems.
• Own observability, performance and reliability rather than throwing problems over the wall.
• Make architectural decisions with incomplete information and move quickly.
• Talk directly to customers when that’s the fastest way to understand the problem.
• Help set the technical bar and shape how the engineering team works as we grow.

• You’re genuinely full-stack. You’re strongest in TypeScript/React/Next.js, but you’re comfortable moving into Python/FastAPI and backend systems when the problem requires it.
• You’ve built with LLMs in production. Not just demos. You’ve worked with orchestration, agents, RAG, streaming responses, evals, structured outputs or human-in-the-loop systems.
• You have strong product and UX instincts. You care about trust and clarity in AI products and notice when an interface technically works but feels wrong.
• You can own ambiguous problems. You don’t need a perfectly written spec. You talk to the user, work out what matters and make the call.
• You’re good at debugging. You can trace problems through logs, application code, data and LLM behaviour rather than guessing.
• You’re comfortable with data-heavy products. Large datasets, search, dashboards, structured and unstructured information, performance optimisation.
• You’ve shipped end-to-end. From API design and data modelling through to a polished customer-facing interface.
• You move fast. You know the difference between technical debt worth taking and shortcuts that will hurt us later.
• You want ownership. You’re excited by being one of the people responsible for deciding how the product and engineering organisation should work.

We care more about what you’ve built, how you think and how quickly you learn than where you went to school.

Technical experience we’re looking for

Core

• TypeScript / JavaScript
• React / Next.js
• Python / FastAPI
• PostgreSQL
• Production cloud infrastructure on GCP or AWS
• Building and operating production web applications

Strong signals

• LangGraph, Vercel AI SDK or similar agent / LLM frameworks
• RAG systems and vector databases such as pgvector or Pinecone
• LangSmith, Datadog, Sentry or similar observability tooling
• Tailwind CSS, ShadCN or similar frontend tooling
• Real-time or streaming applications
• Experience with large datasets and natural-language search
• Building products 0 to 1 or scaling an early-stage product

Bonus points

• Previous founding engineer, early startup engineer or CTO experience
• You’ve built AI products used by real customers at meaningful scale
• WhatsApp Business API, Twilio or other messaging/telephony integrations
• Strong design or UX background
• Experience with voice AI, STT/TTS or real-time conversational systems
• You’ve worked directly with customers rather than only through product managers
• You might want to found a company yourself one day

• You want a predictable 9-to-5
• You’d rather work from a detailed backlog than own whole problems
• You want to specialise narrowly in one part of the stack
• You don’t enjoy talking to users or understanding why they’re struggling
• You want technical decisions to come from someone above you
• Five days a week in the office sounds exhausting rather than energising

How we work

We’re an early-stage startup and we work like one.

The pace is fast, the bar is high, and we’re in the office together five days a week. Decisions get made quickly and you own your work. No committees, no waiting for permission.

We’re rebuilding a $1T+ industry and we don’t think that happens on a 9-to-5.

We’re also having fun. The team is small, ambitious and genuinely enjoys building together. If that intensity sounds draining rather than energising, this probably isn’t the right role.

What we offer

• £80K-£120K base depending on experience
• Meaningful founding equity
• Real ownership over the product and technical direction
• Private health insurance
• Dinners in the office
• Brand new MacBook
• Travel covered for customer site visits

But the real offer is ownership. You’ll help decide what we build, how we build it, and what the engineering team becomes as cinnamon grows.

Pay: £80,000.00-£120,000.00 per year

This is an early engineering hire with real ownership. You’ll work across the product end-to-end, from the interfaces customers use every day to the backend systems, agents, data pipelines and integrations that power them.

You’ll make product and technical decisions independently, ship quickly, and own what you put into production.

We’re not looking for someone who wants to pick tickets off a backlog. We want someone who can take a problem, understand the customer need, design the system, build it, ship it, and make sure it works.

What we’re building

Property is one of the most important parts of people’s lives. It’s where you raise your kids. It’s most people’s biggest financial decision. And the experience of buying, selling, or renting one is still shockingly bad.

We live in a world where you can send money across borders in three seconds, hail a car with a tap, and have your entire medical record on your phone. But when it comes to property? You’re waiting for a call back from a branch that closes at 5:30. Your offer is being managed in a spreadsheet. Your tenancy renewal is stuck because someone forgot to send an email. Viewings get lost. Follow-ups slip. Deals die in inboxes.

The infrastructure that powers how people find homes, move between them, and manage their biggest asset has barely changed in 30 years. CRMs built in the 2000s. Processes designed for paper. Compliance workflows held together by memory and sticky notes.

Nobody has built the definitive AI agent layer for real estate yet. That’s what we’re doing.

cinnamon.io is an AI workforce for estate and letting agencies. We build AI employees that handle tenant engagement, landlord outreach, compliance, viewing management, and lead nurturing autonomously. They sit inside the tools agencies already use. They learn from every call, email, and WhatsApp message. They don’t miss things.

Our first AI hire is already live with agencies across the UK, with early US traction. One agency booked 120 viewings over a bank holiday weekend without a single human picking up the phone.

This is what it looks like when an industry finally gets rebuilt from the inside.

About us

• Backed by Entrepreneurs First and top-tier VCs
• Live with agencies across the UK with early US traction
• Building AI agents that don’t just assist. They do the work.