Founding Engineer (AI Startup) (4CA10E8)

Referment; Greater London; On-site; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Competitive salary

Meaningful equity

Direct access to founders

Job summary

Referment is partnering with a venture-backed AI startup to hire an exceptional engineer who will own features end-to-end, from problem to production. You’ll work directly with the founders on building AI-powered cybersecurity products and ship React interfaces while shaping backend systems and internal tools.

You’ll thrive on hard engineering challenges, from DSLs to compiler-like components, and you’ll be deeply involved in design decisions, deployment, and product culture from day one.

Qualifications

• Strong Python backend fundamentals with high-level application of tools like FastAPI, Django, or Flask to build DSLs or agentic infrastructure.
• Verifiable track record of technical contributions and honest project claims, such as an active GitHub or OSS presence where you are a primary maintainer or frequent contributor.

Responsibilities

• Own features from customer problem through to production.
• Design complex backend architecture and systems.
• Ship React interfaces.
• Build internal developer tools, agentic consoles, and custom runner systems.
• Improve databases and handle systems programming.
• Debug production and deploy continuously.
• Help shape both the product and the engineering culture.

Skills

Python

Backend architecture

FastAPI/Django/Flask

React

OSS contributions

Tools

FastAPI

Django

Flask

Job description

Some engineers enjoy writing code. Others can't stop building.

If you've been programming since you were a teenager, spend your evenings experimenting with new technology, and get genuine satisfaction from shipping products, this role was written for you.

Referment is partnering with a venture-backed AI startup looking for one exceptional engineer to help build the next generation of AI-powered cybersecurity products.

You'll work directly with the founders and own features from customer problem through to production.

You’ll enjoy this role if you...

• Love building more than talking about building
• Prefer shipping software over writing documentation
• Can move between backend, frontend and infrastructure without thinking twice
• Get excited by hard engineering challenges like building compilers, DSLs, or internal developer tools
• Use AI every day, but don't rely on it to think for you
• Enjoy solving messy customer problems instead of perfectly defined tickets
• Identify as a natural builder with complex side projects like developing programming languages or agentic engines from scratch

What You’ll Be Building

Rather than owning a small corner of a huge codebase, you'll own products end-to-end

• You'll design complex backend architecture and systems.
• Ship React interfaces.
• Build internal developer tools, agentic consoles, and custom runner systems.
• Improve databases and handle systems programming.
• Debug production and deploy continuously.
• Help shape both the product and the engineering culture.

What We're Looking For

• Deep technical focus on hard engineering and complex backend architecture rather than just feature delivery
• Strong Python backend fundamentals with high-level application of tools like FastAPI, Django, or Flask to build DSLs or agentic infrastructure
• Senior-level technical sophistication and the ability to move beyond routine maintenance tasks
• Verifiable track record of technical contributions and honest project claims, such as an active GitHub or OSS presence where you are a primary maintainer or frequent contributor
• React experience or willingness to work across the frontend
• Startup mentality with genuine product ownership
• Around 3-6 years' experience with a focus on engineering depth

Extra points for experience with:

• Founding or leadership roles (e.g. Co-Founder, CTO, or Founding Engineer)
• Building internal developer tools, agentic consoles, DSLs, or compilers
• Multi-language proficiency in systems languages like Go, C, or Rust
• Cybersecurity
• Workflow orchestration (Prefect, Airflow)
• High-growth SaaS

This probably isn't for you if:

• Your focus is primarily on product management or innovation titles rather than hands-on engineering
• You consider routine infrastructure maintenance, such as managing Linux servers, to be your core focus area
• You need detailed specs before starting work
• You only enjoy one part of the stack
• You avoid production responsibility
• You're looking for a comfortable corporate engineering role
• You're currently splitting your attention with another startup

Why join?

• Competitive salary
• Meaningful equity
• One of the first engineering hires
• Direct access to the founders
• Huge ownership from day one
• Build products that customers actually use

#Referment