Senior Backend Engineer (.Net)

Senior Backend Engineer (C#/.NET)

London Bridge (Hybrid)

The Opportunity & The Company

Twelve are partnered with a high-growth B2B technology vendor solving complex data aggregation, visibility, and risk-management challenges for enterprise organisations. Their platform unifies a vast ecosystem of third-party tools into a single, real-time source of truth, allowing customers to secure and manage their critical digital assets with ease.

Having spent years building a highly accurate, large-scale dataset, they are now entering their next major growth phase: layering advanced AI capabilities on top of their core platform to automate workflows and predict risk.

As a Senior Backend Engineer, you will report directly to the Head of Engineering, working on complex system architecture, high-throughput data pipelines, and the backend infrastructure required to feed LLMs with real-time data.

What You'll Do

• Architect & Scale: Design and evolve a core multi-tenant architecture, integration frameworks, and APIs to handle massive enterprise data flows.
• Drive AI Integration: Build the robust data pipelines and backend services necessary to stream accurate, real-time data into LLMs.
• Solve Complex Data Challenges: Tackle event correlation, high-throughput processing, and security-first backend engineering.
• Raise the Bar: Mentor other engineers through code/design reviews and promote strong architectural thinking across the team.

What We Are Looking For

• Deep C#/.NET Expertise: Strong system design instincts with the ability to write clean, scalable, and maintainable code.
• Cloud & SaaS Experience: Proven track record working on multi-tenant SaaS platforms built on cloud infrastructure (AWS or equivalent)
• Data & API Design: Strong database architecture skills and experience building fast, secure, and reliable APIs.
• AI Curiosity: An interest in AI and LLMs, and an excitement for building the backend systems that make these features possible.
• Leadership: Experience mentoring engineers and raising technical standards across a team.
• Bonus points if you have experience building integration platforms or connector frameworks.

Why Join?

• Cutting-Edge Tech: Work at the intersection of enterprise data, cloud infrastructure, and AI.
• High Impact: High-growth opportunity (post-investment) to play a pivotal role in shaping the core architecture of an established, scaling platform.
• Collaborative Culture: Work alongside a highly talented engineering team that genuinely cares about engineering excellence.
• Prime Location: Great hybrid working setup based out of a vibrant London Bridge office.

How to Apply

If you are an experienced Backend Engineer (.Net) looking to tackle genuinely complex engineering challenges, we want to hear from you. Please apply with your CV via the link below to initiate a confidential discussion.