Backend Software Engineer – AI Platform (Remote UK)

System1; United Kingdom; Remote; GBP 80,000 - 105,000; Full time

Benefits offered by this job

Health insurance

Pension

Remote working within the UK

Education reimbursement

Wellbeing resources

Recognition schemes

Job summary

System1, based in the UK, is building an AI-native platform to help the world's largest brands predict and improve advertising effectiveness. We are seeking a Backend Software Engineer to join a cross-functional product team and help shape the next generation of Python services and integrations.

You will work closely with product management, design and data science to deliver scalable, API-first backend systems, while advocating for reliability, security and production readiness across the stack.

Qualifications

• 3–5 years of real-world software engineering experience.
• Strong backend in Python.
• Experience designing and building REST APIs, ideally spec-driven.
• Experience building SaaS software and production-scale code.
• Hands-on experience with at least one major cloud platform (AWS/Azure/GCP).
• Working understanding of infrastructure as code.
• Solid experience with data modelling.
• Experience building MCP servers.
• Experience in a product operating model with cross-functional teams.
• Familiarity with security and compliance for enterprise customers.
• Familiarity with machine learning systems or eagerness to learn.

Responsibilities

• Partner in an empowered product team with PM, designer, TL and engineers.
• Contribute to product discovery and build quick prototypes to test ideas.
• Design, build and own Python backend services for the AI platform.
• Work API-first and define REST contracts for frontends, internal teams and integrations.
• Build MCP servers exposing System1 data and capabilities to agents and tools.
• Engineer with Claude Code day-to-day to create skills and subagents.
• Take code to production with testing, observability and reliability.
• Contribute to infrastructure as code and cloud deployment practices.
• Collaborate with data scientists to bring models to production.
• Maintain security and compliance for enterprise customers.
• Explain technical trade-offs to stakeholders and teammates.

Skills

Python backend

REST APIs

SaaS experience

Cloud platforms (AWS/Azure/GCP)

Claude Code usage

MCP servers knowledge

Product team collaboration

Data modelling

Security/compliance awareness

Problem solving

Job description

System1, based in the UK, is building an AI-native platform to help the world's largest brands predict and improve advertising effectiveness. We are seeking a Backend Software Engineer to join a cross-functional product team and help shape the next generation of Python services and integrations.

You will work closely with product management, design and data science to deliver scalable, API-first backend systems, while advocating for reliability, security and production readiness across the stack.