Senior Full-Stack Engineer
Plan:it · London Area, United Kingdom
About this role
This is a senior full-stack engineering role at an early-stage, well-funded AI startup. The engineer will build features end-to-end, maintain shipped code, and work directly on top of agentic systems and LLM-powered features. The technical stack includes TypeScript, React, AWS, and GCP. As the fourth engineer on the team, you will operate with high autonomy and minimal oversight in a small, high-performing team. The role requires a high-agency individual who is comfortable across the UI, API, and database layers.
Skills & technologies
Must have
Nice to have
- agentic systems
- LLM-powered features
Read full description
💻 Senior Full-Stack Engineer (AI)
💰 Up to £130,000 + equity
📍 London / hybrid, 3–4 days per week in the office
🚀 AI Startup
This is a rare opportunity. Chance to join an early-stage startup as engineer #4. Autonomy, responsibility and working with cutting edge AI.
Company:
A well-funded, early-stage startup building a genuinely AI-native product. AI at the core, with agentic systems already running in production. Small team, high standards, and an awesome team culture.
The Role:
This is a senior full-stack engineering role for someone who thinks in systems, not just tickets. You'll build features end-to-end, maintain what you ship, and raise the quality bar across the codebase. The team is small, so you'll touch most parts of the stack most weeks - and you'll be expected to operate with minimal oversight.
Key responsibilities:
- Build features end-to-end
- Spot and fix rough edges before users do
- Build directly on top of agentic systems
- Use AI tooling daily to plan, write, review, and ship code faster
Stack:
TypeScript, React, AWS, GCP. Agentic systems and LLM-powered features already in production.
You'll be a good fit if you...
- Early-stage or startup experience is a must!
- Have 6+ years of professional software engineering experience - ideally with real ownership
- Are genuinely comfortable across the full stack - UI, API, and database
- Already use AI tooling daily - coding assistants, agents, or similar. This is a must
- Have hands-on experience with agentic systems or LLM-powered features in production (nice to have)
- Are high agency you find work that needs doing and do it
💚 Why join?
🎯 Real ownership
🤖 AI-native from the ground up
🚀 High-performing team
📈 Equity that could matter
🌴 Opportunities to travel + great benefits
The Package:
- Up to £130k base (DoE) + equity
- 30 days holiday
- London - hybrid, 3–4 days per week in the office
Interview Process:
- 30-min intro call
- Tech Test
- On-site final and meet the team
- Offer 🙌
Please only apply if you live in or near London and are happy to commute 3/4 days per week.
