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# Backend Software Engineer

- **Company:** Postaladdress
- **Location:** London, UK
- **Experience:** Expert
- **Salary:** £80,000.0 - £160,000.0
- **Contract:** Permanent contract
- **Skills:** Application Programming Interfaces (APIs), Artificial Intelligence, Software Debugging, Distributed Systems, Large Language Models, Backend, Data Pipelines, Golang
- **Published:** September 5, 2026
- **Apply:** https://startup.jobs/backend-software-engineer-golang-london-reflexivity-8632085

## About the Role

You own critical services and improve their performance or reliability.

After 12 months:
You influence architecture decisions and mentor other engineers.

Who You Are (Must-Haves)

 * 5 plus years backend engineering experience
 * Strong Golang experience in production systems
 * Startup experience on a core product
 * Experience working with data-heavy systems
 * Comfortable using AI-assisted coding tools daily
 * Fintech or investment domain exposure

Nice-to-Haves

 * Experience supporting ML or LLM systems
 * Distributed systems or low-latency data pipelines

How We Work

 * Engineers own systems end to end
 * Clear accountability and direct feedback
 * In-office team with high trust and high ownership

## Description

You build backend systems that stay up when things get ugly.
You care about correctness, performance, and clarity over cleverness.
You want your code to power decisions involving real money.
If you have only worked on internal tools or low-impact services, this is not the role.

The Role, In Plain English

You will build the backend systems that power Reflexivity's AI-driven investment platform.
This role exists because scale, data complexity, and latency matter deeply in finance.
You will work closely with AI and product teams to ship production-grade systems.

What You'll Be Responsible For

 * Build and maintain Golang services that power core product workflows
 * Design APIs and data pipelines used by AI and reasoning systems
 * Improve system performance, reliability, and observability
 * Review and challenge designs to keep systems simple and scalable
 * Debug production issues with speed and discipline


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