Founding Engineer

Salary: £80,000 - 120,000 per year

Requirements:

• We are looking for a genuinely full-stack engineer, strongest in TypeScript/React/Next.js, with comfort working in Python/FastAPI and backend systems.
• We want someone who has built with LLMs in production, including orchestration, agents, RAG, streaming responses, evals, structured outputs or human-in-the-loop systems.
• We value strong product and UX instincts, especially around trust and clarity in AI products.
• We need someone who can own ambiguous problems, talk to users, and make decisions without a detailed spec.
• We are looking for strong debugging skills across logs, application code, data and LLM behaviour.
• We want experience with data-heavy products, including large datasets, search, dashboards, structured and unstructured information, and performance optimisation.
• We expect end-to-end shipping experience, from API design and data modelling through to polished customer-facing interfaces.
• We value fast-moving engineers who understand the difference between healthy technical debt and shortcuts that will cause problems later.
• We want someone excited by ownership and helping shape how the product and engineering organisation work.
• Core technical experience we are looking for includes TypeScript/JavaScript, React/Next.js, Python/FastAPI, PostgreSQL, production cloud infrastructure on GCP or AWS, and building and operating production web applications.
• Strong signals include experience with LangGraph, Vercel AI SDK or similar agent/LLM frameworks, RAG systems and vector databases such as pgvector or Pinecone, observability tooling such as LangSmith, Datadog or Sentry, Tailwind CSS or ShadCN, real-time or streaming applications, large datasets and natural-language search, and 0-to-1 or early-stage product scaling.
• Bonus points for previous founding engineer, early startup engineer or CTO experience, AI products used at meaningful scale, WhatsApp Business API, Twilio or other messaging/telephony integrations, strong design or UX background, voice AI/STT/TTS or real-time conversational systems, direct customer work, or interest in founding a company one day.

Responsibilities:

• Build and evolve the interfaces agency teams use to monitor AI conversations, intervene when needed, configure agent behaviour and understand what is happening across their business.
• Own onboarding flows, authentication, permissions, admin controls, billing and the product surfaces customers use every day.
• Build dashboards and data-heavy interfaces that make large amounts of structured and unstructured information usable.
• Design AI-native interfaces with clear status, editable outputs, graceful fallbacks and human-in-the-loop workflows.
• 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 wider software stack agencies already use.
• Work with PostgreSQL, Redis, vector databases and other infrastructure needed to make the product reliable at scale.
• Take features from customer problem to architecture to production.
• Debug production issues across frontend, backend and LLM systems.
• Own observability, performance and reliability.
• Make architectural decisions with incomplete information and move quickly.
• Talk directly to customers when that is the fastest way to understand the problem.
• Help set the technical bar and shape how the engineering team works as we grow.

Technologies:

• AI
• API
• AWS
• Backend
• Cloud
• CSS
• CRM
• CTO
• Datadog
• FastAPI
• Frontend
• GCP
• JavaScript
• LLM
• MacBook
• PostgreSQL
• Python
• RAG
• React
• Redis
• Sentry
• TypeScript
• Web
• UX UI Design
• AI Agents
• REST

More:

We are building cinnamon.io, an AI workforce for estate and letting agencies. Our AI employees handle tenant engagement, landlord outreach, compliance, viewing management and lead nurturing autonomously, working inside the tools agencies already use and learning from every call, email and WhatsApp message. We are backed by Entrepreneurs First and top-tier VCs, already live with agencies across the UK with early US traction, and have seen our first AI hire help an agency book 120 viewings over a bank holiday weekend without a human picking up the phone. This is an early-stage, in-office role based in Aldgate, London, with travel to customer branches across the UK, five days a week. We offer meaningful founding equity, private health insurance, office dinners, a brand new MacBook, travel covered for customer site visits, and the opportunity to help decide what we build, how we build it and what the engineering team becomes as we grow.

last updated 38 week of 2026