Senior Backend Engineer in London

About Harmonic Security

Harmonic Security lets teams adopt AI tools safely by protecting sensitive data in real time with minimal effort. It gives enterprises full control and stops leaks so that their teams can innovate confidently. We are led by cybersecurity experts and backed by top investors including N47, Ten Eleven Ventures, and In-Q-Tel.

As AI tools rapidly become embedded in everyday workflows, the systems that connect, secure, and make sense of that activity are becoming mission‐critical. This role sits at the core of Harmonic's platform: building the backend services and integrations that power real‐time data protection, visibility, and control across complex customer environments. You'll help design and operate the foundational infrastructure that enables Harmonic to understand user intent, process high‐volume event data, and enforce security decisions at scale. This work directly shapes the product, the customer experience, and the category we're defining.

About the Team

Our Product Delivery team is the engine that turns vision into impact. We ship early and often, getting valuable features into the hands of customers quickly and iterating from there. We work in the open by default, sharing progress and ideas, and we trust each other to own outcomes. We're a small but mighty crew where every person plays a critical role and we're committed to using AI to work smarter and faster.

About the Role

We're looking for a Backend Engineer who has an appreciation for all things security and system interconnectivity. This is a very hands‐on technical role where you will be responsible for designing, building and maintaining scalable integrations between our core applications, identity providers and data security platforms.

What You'll Do

• Own deliveries and features from start to finish
• Design, build, and own backend services in a microservices‐based, event‐driven architecture
• Implement core domain logic that drives key product workflows and system behavior
• Ingest and process high‐volume usage and event data from customer‐facing endpoints
• Build backend services that support operational, analytics, and reporting use cases
• Model, persist, and manage domain data, enabling querying, filtering, and lifecycle management
• Expose well‐designed APIs and webhooks consumed by customers, UIs, and external systems
• Power customer‐facing UI experiences by providing backend APIs for visibility, analytics, and configuration

What Success Looks Like

• Features you've built are widely adopted, reliable, and delivered quickly without sacrificing quality
• Performance, scalability, maintainability, and high engineering standards are baked into every release
• You are seen as a trusted partner by product, design, and engineering peers

What you Bring

• Strong development experience in the Java ecosystem
• Experience building and operating event‐driven systems in distributed architectures
• A track record of delivering performant, reliable and scalable applications
• Excellent collaboration and communication skills in cross‐functional teams

You Might Be a Fit if You...

• Love the idea of blending software development, distributed systems and data‐intensive applications
• Thrive in fast‐paced startup environments where ambiguity is the norm
• Enjoy shaping culture and engineering practices, not just writing code
• See AI as a tool to help you build smarter, faster and better

Why Join Us

This isn't just a job; it's an opportunity to be part of a team that is redefining cybersecurity. We believe today's talent is tomorrow's success, and we're committed to creating an environment where you can do the best work of your life.

• Competitive pay and meaningful equity with a direct stake in Harmonic's success
• Comprehensive benefits, pension plan, generous PTO, and flexible hybrid work
• A small, passionate team that values transparency, creativity, and learning
• Thoughtful leadership that cares deeply about growth, impact, and people
• Annual global offsites (past trips include Lisbon and Nashville)
• The chance to directly shape both our product and our culture as we build a category‐defining company

Harmonic's Core Values

• Flourish in the Unknown: We relish being thrown into new, unfamiliar situations that require initiative and rapid decision‐making. We orient ourselves quickly and deliver results with minimal guidance.
• Never Full: We never hesitate to raise our hands and take on challenges to assist those in need. We hunger for opportunities to learn and do more.
• Perfect Harmony: We have a genuine willingness to assist and support one another to create cohesion and unity. We foster success through collaboration and honest sharing of feedback and ideas, enabling everyone to grow and produce their best work.