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Junior

Senior Backend Engineer - London

Reposted 14 Days Ago
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In-Office
London, Greater London, England, GBR
Mid level
In-Office
London, Greater London, England, GBR
Mid level
As a Backend Engineer, you will build AI-first internal tools, develop data architecture, and automate processes for the commercial team.
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About Junior

We’re building cutting-edge LLM-powered workflow tools to supercharge investment research for private market investors. Our clients include most of the global top 10 private equity and consulting firms - Junior already powers hundreds of billions of dollars invested annually. We’re a profitable, bootstrapped company with a growing team of 40+ based in London, NYC and Sydney. We 10x’d our revenue in 2025.

You can read more about the company mission & values here.

Role Description

You’ll build and scale the systems that power our AI-driven research products and enable our operations / sales teams to deliver our product as efficiently as possible. This is a systems-level role - ideal for engineers who love thinking about data flows, orchestration, and performance across complex distributed systems.

You’ll have the opportunity to:

  • Ship quickly

  • Architect and scale backend systems that support high-throughput LLM interactions, vector search, and multi-agent orchestration.

  • Stitch together AI infrastructure across model providers, data stores, and internal APIs to create cohesive, performant systems.

  • Prototype new backend capabilities (retrieval pipelines, caching layers, async task queues) that let us build faster and smarter

  • Own the architecture of internal data systems and pipelines

  • Build automation and integrations across product, CRM, and financial systems

  • Help shape engineering culture and internal infrastructure decisions

About You

We’re looking for a Backend Engineer who enjoys building systems that make a company run better.

You might be a good fit if you:

  • Are based in London and excited to work from our Farringdon office (5 days/week)

  • Have experience owning technical projects end-to-end, from architecture through production

  • Are excited by the intersection of AI infrastructure, financial systems, and backend engineering

  • Enjoy translating business problems into clean technical systems and automation

  • Have worked with PostgreSQL and care about data modelling, reliability, and system design

  • Write production code in Python, or TypeScript

  • Are comfortable building APIs, internal tools, workflows, and infrastructure that support real customers

  • Thrive in fast-moving startup environments and enjoy shipping quickly while maintaining strong engineering standards

Bonus points for experience working on:

  • Billing, payments, usage-based pricing, or financial workflows

  • Internal infrastructure / dev tools at startups

  • Data pipelines, workflow orchestration, or event-driven systems

  • Retrieval, embeddings, or prompt orchestration

Why Junior

  • Top 1% traction: 0-20+ m rev in 3 years, fully bootstrapped / profitable, top-tier customers inc. some of MBB, Big 4, Top 5 PE mega-funds

  • Flat org structure: lean startup environment – every engineer reports directly to the CTO / co-founder

  • Competitive salary + equity and first-class benefits inc:

    • Lunch + dinner provided in-office

    • Third Space membership

    • Private health insurance

    • Multiple all-expense paid offsites per year (last 3 trips include Crete, Greece; Cancun, Mexico; Barcelona, Spain)

    • Visa sponsorship available

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