Founding Backend Engineer | Python, TypeScript, LLMs, RAG | Seed-Funded B2B SaaS | £100,000 - £[...]

Owen Thomas | Pending B Corp; City Of London; Hybrid; GBP 100,000 - 160,000; Full time

Job summary

A well-funded B2B SaaS startup is looking for a Founding Backend Engineer to architect and implement core AI features. This hands-on role involves designing AI workflows, developing scalable data processing pipelines, and collaborating closely with the founding team. Ideal candidates will have strong backend experience, especially in Python, along with expertise in LLMs and cloud technologies. The position offers a competitive salary of £100,000 - £160,000 and early-stage equity, with a hybrid working model based in East London.

Benefits

Salary up to £140,000

Meaningful equity

Chance to shape company culture

Real-world AI problems

Qualifications

• Strong backend engineering experience, preferably in Python.
• Experience in production with LLMs, NLP or applied machine learning.
• Understanding of data pipelines and distributed systems.

Responsibilities

• Architect and build production-grade AI features.
• Design AI-powered workflows for data.
• Develop scalable pipelines and APIs in Python.

Skills

Backend engineering

Python

Working with LLMs

NLP

Cloud experience

Data processing

Communication

Tools

AWS

GCP

Azure

Job description

Founding Backend Engineer | Python, TypeScript, LLMs, RAG | Seed-Funded B2B SaaS | £100,000 - £160,000 + Early Stage Equity | London, Hybrid | Can Sponsor + Relocate

The Company

We’re supporting a well-funded Seed‑stage B2B SaaS startup backed by top‑tier European investors.

They are automating a traditionally manual, data‑heavy operational process that sits at the heart of large online businesses. The platform is already in use with several enterprise customers, and funding has been secured to scale engineering and deliver an AI‑driven product roadmap.

You’ll be joining very early, working with an experienced founding team who have previously built and scaled well‑known tech companies.

The next phase is product expansion, deeper automation, and building intelligent systems that turn unstructured data into actionable insights at scale.

About the Founding Backend Engineer | Python, TypeScript, LLMs, RAG | Seed‑Funded B2B SaaS | £100,000 - £160,000 + Early Stage Equity | London, Hybrid | Can Sponsor + Relocate

As the Founding AI Engineer, you will architect and build production‑grade AI features into the core platform. The role blends backend engineering, data processing, and practical AI / LLM deployment.

Your work may include :

• Designing AI‑powered workflows for unstructured and semi‑structured data
• Building intelligent document processing, matching and extraction
• Developing scalable pipelines and APIs in Python
• Working on retrieval, embeddings, and search
• Productionising LLM‑driven features for real customers

This is a hands‑on engineering role with high ownership. You will collaborate directly with the CTO and founding engineers, and have real influence over architecture, model choice, tooling and product direction.

Requirements

• Strong backend engineering experience (Python preferred)
• Experience working with LLMs, NLP or applied machine learning in production
• Understanding of data pipelines, distributed systems or large‑scale processing
• Cloud experience (AWS, GCP or Azure)
• Comfortable in fast‑paced, high‑ownership environments
• Excellent communication and product mindset

Experience in a startup or scale‑up is a strong advantage, but not required if you can demonstrate ownership of end‑to‑end systems.

What’s on Offer

• Up to £140,000+ salary + meaningful early‑stage equity
• Hybrid working, East London office (3‑4 days per week)
• Chance to shape technical strategy and culture from day one
• Real‑world AI problems with paying customers and immediate impact
• Long‑term progression into Principal or Head of AI

If you’re interested in the Founding Backend Engineer | Python, TypeScript, LLMs, RAG | Seed‑Funded B2B SaaS | £100,000 - £160,000 + Early Stage Equity | London, Hybrid | Can Sponsor + Relocate, apply today. If your background fits, we’ll reach out to discuss next steps.