Senior Backend Engineer (£100k-£140k + Equity) at Myjunior

This is a job that Jill, our AI Recruiter, is recruiting for on behalf of one of our customers. She will pick the best candidates from Jack's network. The next step is to speak to Jack. Job Title Senior Backend Engineer Salary £100k-£140k + Equity Company Description Myjunior.ai is a profitable, bootstrapped London startup building LLM-powered workflow tools that supercharge investment research for global top 10 private equity and consulting firms. Job Description As a Senior Backend Engineer at Myjunior.ai, you will architect and scale systems supporting high-throughput LLM interactions, vector search, and multi-agent orchestration. You will design data pipelines and internal infrastructure that powers investment research for the world's leading firms, taking high ownership of projects from architecture through to production. Location London, UK Why this role is remarkable Join a hyper-growth team that 10x'd revenue in 2025 while remaining fully bootstrapped and profitable, working directly with the CTO/co-founder. Build the core infrastructure powering hundreds of billions in annual investment for the world's most prestigious private equity mega-funds and MBB firms. Enjoy first-class perks including Third Space memberships, daily office meals, and regular all-expense-paid international offsites to locations like Crete, Cancun, and Barcelona. What You Will Do Architect and scale backend systems for high-throughput LLM orchestration, vector search, and complex multi-agent workflows. Design and own internal data platforms that consolidate product usage, CRM data, and financial systems to drive business intelligence. Stitch together AI infrastructure across model providers and data stores to create performant, retrieval-heavy research pipelines and internal automation. The ideal candidate Has 4+ years of professional experience building and scaling distributed backend systems using Python or TypeScript and PostgreSQL. Demonstrates a proven track record of owning technical projects end-to-end, translating complex business problems into clean, reliable production code. Thrives in a fast-paced startup environment and is excited to work in-person at the Farringdon office alongside a high-caliber engineering team. Who are Jack & Jill? Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support. And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate. How does this work? Jack's an AI agent for job searching and career coaching. He works for you. Jill is the AI recruiter working for the company. She recruits from Jack's network. If it's a match and the company wants to meet you, they'll make the intro. In the meantime, if you'd like, Jack will send you excellent alternatives. We never post fake jobs This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network. Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description. We appreciate this can make them look a bit suspect, but there isn't much we can do about it. Give Jack a spin! You could land this role. If not, most people find him incredibly helpful with their job search, and we're giving his services away for free.