Senior Product Engineer (Python / Go / TS ) | Production Agentic AI | B2C Start-up, Series A | £100k-£250k + Equity | London (5 Days) | Visa Sponsorship + Relocation

Owen Thomas B Corp; Greater London; On-site; GBP 100,000 - 250,000; Full time

Benefits offered by this job

Equity

Visa sponsorship

Relocation support

London-based team

Benefits package

Job summary

Owen Thomas B Corp in London is seeking a Senior Product Engineer to design, build and scale backend services powering real-world AI applications. You will own features end-to-end, from architecture through production, collaborating with product teams and engineers.

The role emphasizes strong backend engineering, API design, and hands-on experience deploying LLM-powered applications in a fast-growing startup environment. Visa sponsorship and relocation support are provided as part of the package.

Qualifications

• 3+ years of commercial software engineering experience.
• Hands-on experience with backend systems and production-grade APIs.

Responsibilities

• Design, build and scale backend services.
• Develop production-grade AI applications and agent workflows.
• Implement robust APIs, data pipelines and async processing.
• Work on AI infrastructure and integration with product features.
• Take ownership from design to production and collaborate with stakeholders.

Skills

Backend engineering

LLM production

APIs

SQL

System design

Performance

Startup experience

Product mindset

Communication

Job description

Senior Product Engineer (Python / Go / TS) | Production Agentic AI | B2C Start-up, Series A | £100k-£250k + Equity | London (5 Days) | Visa Sponsorship + Relocation

Company Name: Owen Thomas B Corp

Job Role: Senior Product Engineer (Python / Go / TS) | Production Agentic AI | B2C Start-up, Series A | £100k-£250k + Equity | London (5 Days) | Visa Sponsorship + Relocation

Job Type: Full Time

Location: London, London, United Kingdom

The Opportunity

We’re working with a well-funded, high-growth technology start-up, with global presence, that’s making a significant investment into its engineering team in London.

They’re looking for exceptional Product Engineers with strong backend experience who want to work on technically challenging problems at the intersection of Software engineering, Product ownership and AI.

The business is already generating revenue, has an established product in production and is now entering an exciting period of growth.

This is an opportunity to join a small, ambitious engineering team, take genuine ownership of what you’re building and have a direct impact on the direction of the product.

Why is this exciting?

• £100k–£250k + Equity – Highly competitive compensation with meaningful long-term upside. Exceptional benefits too.
• Production AI – Work on real-world AI systems, not experimental proof-of-concepts or another basic LLM wrapper.
• Technical ownership – Make important architectural decisions and take responsibility for features from idea through to production.
• Strong engineering culture – Work alongside experienced engineers who care about building excellent products and solving difficult problems.
• Early-stage opportunity – Join while the engineering team is still relatively small, with significant room for personal and technical growth.
• Career progression – Opportunity to grow into Staff, Principal or Engineering Leadership positions as the business scales.

The Role

We’re looking for strong, product-minded Backend Engineers who enjoy building reliable, scalable systems and solving complex engineering challenges.

You’ll have significant autonomy, working across backend architecture, AI infrastructure and product development.

This isn’t a role where you’ll simply be handed tickets to complete. You’ll be expected to understand the problems you’re solving, challenge assumptions and take ownership of delivering the right solutions.

What you’ll be working on

• Designing, building and scaling backend services
• Developing production-grade AI applications, agent workflows and LLM integrations.
• Building and improving APIs, asynchronous processing systems and data pipelines.
• Working on agent orchestration, retrieval systems and AI infrastructure.
• Improving reliability, performance and scalability across cloud-native systems.
• Taking ownership of features from initial design through to production.
• Collaborating closely with engineers, product teams and other stakeholders.

What we’re looking for

• 3+ years of commercial software engineering experience.
• Strong backend engineering experience
• Hands-on experience building and deploying LLM-powered applications or agentic AI systems into production.
• Strong engineering fundamentals across APIs, SQL, system design and performance.
• Experience working in a start-up or fast-paced product engineering environment.
• A genuine product engineering mindset, with the ability to understand business problems and translate them into technical solutions.
• Excellent communication skills, strong ownership and a proactive approach to problem-solving.

Nice to have: Go, Django, GCP, Terraform, Celery, RAG, multi-agent systems and LLM evaluation frameworks.

What’s On Offer?

• £100,000–£250,000 base salary + meaningful equity.
• Opportunity to join a well-funded technology start-up at an exciting stage of growth.
• Significant technical ownership and influence over architecture.
• Work on sophisticated AI systems operating in production.
• Clear progression opportunities as the engineering team expands.
• Comprehensive benefits and professional development support.
• Visa sponsorship and relocation support available.
• London-based engineering team, working predominantly in person.