Senior Software Engineer

AI is being run everywhere, by humans and agents. Harmonic Security governs all of it. The AI Governance and Control (AIGC) platform understands user / agent intent and data context in real time, giving security teams visibility and control across every tool and workflow so companies can move faster with AI while minimizing risk.

We operate in one of the fastest-moving spaces in tech: the emerging intersection of AI and cybersecurity. It's a market still being defined, and we're among the first to build natively for it - protecting sensitive data in real time, at the endpoint, with minimal friction for the teams using it. Enterprises get full visibility and control. Their people get to innovate without guardrails slowing them down.

Named to the Rising in Cyber 2026 list, Harmonic is gaining serious recognition and serious traction. We're led by deep cybersecurity expertise and backed by investors who know the space: N47, Ten Eleven Ventures, and In-Q-Tel.

As AI adoption inside the enterprise accelerates, the ability to safely observe, control, and enforce policy in real time isn't a nice-to-have. It's mission-critical infrastructure. That's what we build.

01How We Work: AI-First by Design

Harmonic exists to help enterprises adopt AI safely and at scale. We hold ourselves to that same standard. Everyone here actively leverages AI tools to perform their best work, from deep research and writing to building robust processes and automating complex workflows. We expect every new hire to bring a genuine curiosity for AI and a commitment to using it to work smarter, faster, and with greater creativity.

For some, this involves tinkering and remaining open to emerging tools; for others, it means architecting entirely new systems with AI at the core. We will be transparent about expectations for every role and provide the tools and support needed for you to thrive.

02About 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.

03About the Role

We’re looking for a Senior Software Engineer to join our Intercept team, which builds the Endpoint Agent and Browser Extension that run on our customers' devices, and the backend services behind them. You'll be a full-system contributor. You'll design and build complex Java backend services and make significant contributions to the agent's Rust codebase and the extension's TypeScript codebase. This software has to be fast, resilient and trustworthy across operating systems and real-world conditions.

Java is the foundation. You don't need expert-knowledge of Rust or TypeScript yet, but you must be willing and able to learn them and comfortable working across all three. You'll join a fast-moving team that ships often and cares about correctness, observability and maintainability.

04What You'll Do

• Own deliveries and features from start to finish, across backend services, the Endpoint Agent and the Browser Extension

• Design, build, and own Java backend services in a microservices-based, event-driven architecture

• Ingest and process high-volume event data from the agents and extensions running on customer devices

• Expose well-designed APIs used by the Endpoint Agent, Browser Extension, UIs, and external systems

• Make significant contributions to the Endpoint Agent in Rust across Windows, macOS and Linux, and to the Browser Extension in TypeScript across Chromium, Firefox and Safari

• Build robust tests, validation tooling and deployment mechanisms for releases that customers rely on every day

• Investigate and resolve platform-specific issues with precision and speed

• Work closely with security engineers, other engineers, and product stakeholders to shape technical requirements

05What You Bring

• 5+ years of professional software engineering experience, mostly building backend services and distributed systems in the Java ecosystem (Java, Spring Boot, Maven/Gradle)

• Some experience in a systems programming setting, such as Rust, C++, or native software running on user devices

• A solid grasp of systems programming concepts: memory safety, concurrency, error handling and IPC

• Experience with Rust or TypeScript is a bonus. You must be willing and able to learn whichever you don't know

• Strong understanding of event-driven architectures, asynchronous processing patterns, messaging systems, and distributed system design

• Proven experience designing and maintaining APIs and service-to-service integrations

• Comfortable operating in AWS, GCP, or Azure environments and working with modern observability tooling, logging, and monitoring platforms

• A track record of delivering performant, reliable and scalable applications

• Excellent collaboration and communication skills in cross-functional teams

06You Might Be a Fit if You

• Learn quickly and independently, and are happy with a wide variety of work

• Understand how the whole system fits together, from backend services to the code running on a user's device, and why architectural decisions matter

• Know when to move fast and when to slow down, and make careful decisions in security-critical code

• Test and validate rigorously, and care about building bulletproof software that runs reliably around the clock

• Have led a technical initiative, or want to grow into leading one

• Have worked with OS platform APIs on Windows, macOS or Linux, or built browser extensions

• Have experience building products in cybersecurity, identity, data protection, or enterprise SaaS environments

• Thrive in fast-paced startup environments where ambiguity is the norm

• Leverage AI tools as an engineer to help you build smarter, faster and better

07Why Join Us

This isn't just a job - it's a chance to help define a category. Harmonic Security was named to the Rising in Cyber 2026 list, and we're just getting started. We're building at the intersection of AI and security, carving out an emerging market where the rules haven't been written yet, and the people who join now will write them.

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.

• Recognized momentum - We made the Rising in Cyber 2026 list, a signal that the market is taking notice

• Rare market opportunity - Join early in a category-defining company at the convergence of AI and security, where your work directly shapes how enterprises tackle one of the biggest unsolved problems in tech

• Competitive pay and meaningful equity - A real stake in Harmonic's success, not a token gesture

• Comprehensive benefits - pension plan and flexible hybrid work

• A small, high-trust team that values transparency, creativity, and continuous learning - no politics, no bureaucracy

• Thoughtful leadership - that cares deeply about your growth, not just your output

• Annual global off-sites - past trips include Lisbon, Portugal and Nashville, TN

• Real ownership - you'll shape the product, the culture, and the direction of the company from day one

08Harmonic's Core Values

🌱 Flourish in the Unknown

We embrace new, unfamiliar situations that require initiative and rapid decision-making. We orient ourselves quickly and deliver results with minimal guidance.

🔥 Never Full

We raise our hands, take on challenges, and assist others whenever possible. We hunger for opportunities to learn and do more.

🤝 Perfect Harmony

We support one another to create cohesion and unity. We collaborate openly, share feedback honestly, and help everyone produce their best work

Compensation: £103K, £114K • Offers Equity

• London, United Kingdom • £103K, £114K • Offers Equity

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