Senior Backend Engineer - London

👶 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 30+ based in London, NYC and Sydney. We 10x’d our revenue in 2025. You can read more about the company mission & values here https://myjunior.notion.site/join-junior-2026?source=copy_link. 💡 ROLE DESCRIPTION You’ll design and build the systems that support our you’ll help build and scale the systems that power our AI-driven research platform along with our commercial, product, and operations teams — automating workflows, improving decision-making, and enabling the company to move significantly faster. This is a high-ownership backend engineering role (~4+ years experience) where you’ll work across data pipelines, integrations, automation, and internal infrastructure. You’ll have the opportunity to: - 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. - 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 🔧 EXAMPLE PROJECTS YOU’LL WORK ON: Customer Health Intelligence System - Design data pipelines that consolidate product usage, CRM data, and user feedback into a unified system of record. - Build automated signals and alerts that detect churn risk, usage drops, or emerging product issues - enabling the team to act quickly. User Feedback → Product Development Pipeline - Build internal tooling that processes feedback calls with users. - Use LLMs to extract themes, cluster feature requests, and surface the most important insights to the product team. Billing & Revenue Infrastructure - Design systems to support complex B2B pricing models — combining usage-based, seat-based, and platform fees. - Automate invoicing, reconciliation, and financial reporting. Internal Data Platform - Build and own our internal data platform, integrating product telemetry, CRM data, and financial systems. - Create reliable pipelines and APIs that power reporting, automation, and decision-making across the company. 🔥 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 • Enjoy translating business problems into clean technical systems and automation • Like building high-leverage internal platforms that make teams dramatically more efficient • Have strong experience with PostgreSQL and modern data platforms (Snowflake, BigQuery, Databricks, Firebolt, etc.) • Write production code in Python, or TypeScript • Thrive in fast-moving startup environments and enjoy shipping quickly while maintaining strong engineering standards Bonus Experience building AI-enabled workflows, automation systems, or internal developer platforms. 🌵 BENEFITS • Private health insurance • Gym membership (Third Space) • Dinner when working late • Frequent team offsites (Crete 🇬🇷, Upstate NY 🇺🇸, Cancun 🇲🇽)