Senior Software Engineer

SR2 Clean Energy; Greater London; On-site; GBP 125,000 - GBP 150,000; Full time

Job description

Senior Software Engineer | London | £100,000 | Security | Python

Location: London (hybrid)

Salary: £90,000 – £100,000 (+/- 10% DOE) + benefits

This is a proper backend role, not a support function.

You’d be joining a security startup where the systems you build are the product, powering complex, compute heavy workflows that need to be correct, observable, and resilient under pressure.

If you enjoy owning things end to end and thinking hard about failure modes, you’ll like this.

What you’d be doing

• Designing and building core backend services in Python using modern async frameworks
• Owning high throughput asynchronous pipelines and background processing
• Working on distributed systems where reliability actually matters
• Turning technically complex research work into production grade services
• Partnering closely with product, security and AI researchers
• Influencing architecture and technical direction rather than inheriting it

The ideal candidate is someone who has built and operated backend systems that actually see production traffic and understands that good engineering is as much about judgment as it is about code. You’re comfortable working in ambiguity, you ask the right questions early, and you take responsibility for the outcomes of the systems you build.

You care about how things fail, not just how they work on a good day, and you’re confident collaborating with researchers and specialists to turn complex ideas into reliable, usable products.

The environment

• Innovative and adult engineering culture
• Backend microservices running on Kubernetes
• Heavy use of async processing, queues, APIs and data pipelines
• High autonomy, high expectations, very little hand holding

You’ll probably be a good fit if

• You’ve spent years building and operating backend systems in production
• Python is a core language for you
• You’re comfortable with async workloads, queues and distributed systems
• You care about correctness, performance and observability
• You like startups, but not chaos
• You want ownership rather than tickets

Logistics

• London based – hybrid
• Security focused domain with real world impact
• Must be eligible for UK security clearance

This won’t suit someone looking for something mundane. It will suit someone who wants to build serious systems in a security first startup, alongside smart people who care about getting it right.

If that sounds like you, or someone you know, drop me an email at .