Full Stack Engineer
Junior AI · London
What this role requires
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Also mentioned, not required: React, English (B2). Worth having, but their absence is not what gets a CV filtered out.
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Job description
👶 About Junior
Junior is building the AI operating system for investment research. Our software helps private equity firms, consultants and financial institutions complete high-stakes research workflows dramatically faster - from diligence and memo writing to market mapping, research synthesis and strategic analysis.
We’re trusted by several of the world’s top private equity firms, Big Four consultancies and leading financial institutions.
Bootstrapped and profitable
~£20M+ in revenue, after growing 10x last year
Read the full description (47 more sections)Show less
60+ people across the company
20-person engineering team, doubling to 40 this year
Core stack: TypeScript, Next.js and PostgreSQL
You’d be joining early enough to shape the product, engineering culture and company, but with enough traction that everything you build lands immediately in front of demanding, paying customers.
💡 The role
You’ll own features end to end - across the frontend, backend and data layer - and ship on a weekly cadence, not a quarterly one.
You’ll:
Ship quickly, then ship again
Design and build entirely new ways of working with computers
Work on groundbreaking projects involving LLMs
Speak directly with the clients using what you build
Use those conversations to shape product decisions
Help define Junior’s engineering culture as the team doubles
🔧 Sample projects
Build frontier products capable of ingesting new types of research inputs
Build an extremely low-latency, voice-to-voice survey tool that autonomously conducts high volumes of research
Build a mobile app from scratch in three weeks
Create segmented knowledge graphs using unstructured-to-structured data transformations
Build an AI-native CRM with deep links into that knowledge graph
🔥 About you
You have 3+ years of engineering experience - we care about demonstrated competence, not pedigree
You’re genuinely strong in TypeScript, Next.js and PostgreSQL, not merely familiar with them
You can build a polished React/Next.js interface or work through a difficult TypeScript problem live and quickly, without relying on Copilot
You have solid foundations in data structures, system design and PostgreSQL
You’re high-agency and product-minded
You’ve owned projects end to end, argued for what should be built - not only how - and shipped without being handed a detailed specification
You communicate clearly and want a client-facing role
You’re based in London, or already committed to relocating, and excited to work with the team in person in Farringdon
You feel like you’re never building fast enough
Bonus : you’ve built and designed AI-powered products
🧭 Interview process
The process moves in days, not months:
Introductory call : background, motivation and mutual fit
Live technical screen (30-mins ): solving a TypeScript problem live in an IDE with one of our engineers. We optimize for speed and completeness over polish, and the interview is completed without AI tools
On-site Interview : a full afternoon of coding, a system-design whiteboard and a product discussion with one of our PMs
Final Cultural Round : a final conversation about how you work, what motivates you and whether Junior is the right environment for you
Offer : decisions are made collectively and quickly
🌵 Benefits
Private health insurance
Third Space gym membership
Dinner provided when working late
Team lunch provided every day at the office
Frequent international off-sites, recently including Crete and Cancún
If you’re excited to drive innovation at Junior, we’d love to hear from you!
Compensation: £90K – £110K • Offers Equity
Junior/Mid • Estimated Base Salary £90K – £110K • Offers Equity
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