Senior Full Stack Engineer

Posted 2 Days Ago
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London, Greater London, England, GBR
In-Office
Senior level
Artificial Intelligence • Information Technology • Software • Generative AI
The Role
Own and ship end-to-end full-stack features across frontend, backend, and data layers. Build AI- and LLM-powered products, research workflows, knowledge graphs, voice-to-voice tools, and mobile applications. Work directly with clients to shape product decisions, contribute to engineering culture, and deliver rapidly in a client-facing environment.
Summary Generated by Built In
👶 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

  • 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 5+ 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:

  1. Introductory call: background, motivation and mutual fit

  2. 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

  3. On-site Interview: a full afternoon of coding, a system-design whiteboard and a product discussion with one of our PMs

  4. Final Cultural Round: a final conversation about how you work, what motivates you and whether Junior is the right environment for you

  5. 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!

Skills Required

  • 5+ years of engineering experience
  • Strong TypeScript, Next.js, and PostgreSQL skills
  • Ability to build polished React or Next.js interfaces
  • Strong TypeScript problem-solving ability without AI tools
  • Strong foundations in data structures, system design, and PostgreSQL
  • Experience owning projects end to end and making product decisions
  • High-agency and product-minded approach
  • Clear communication skills and interest in a client-facing role
  • Based in London or committed to relocating
  • Experience building and designing AI-powered products
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The Company
HQ: New York City, New York
111 Employees
Year Founded: 2023

What We Do

Junior leverages the power of generative AI to help deal teams and their advisors collaborate more effectively, uncover deeper insights, and accelerate their path to output. Our platform is purpose-built for the diligence process, with custom workflows that streamline how teams extract, structure, and analyze information. We deliver: • Best-in-class transcription with structured extraction of expert call insights • Instant key takeaways automatically generated after each call • Intelligent search across transcripts to pinpoint relevant insights fast • Quantitative tracking to monitor findings across interviews • Custom GPT-based synthesis that lets you query and summarize expert input at scale By integrating seamlessly into your workflow, Junior transforms raw information into actionable intelligence - quickly, accurately, and securely.

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