Full Stack Engineer

At Kertoa, we’re on a mission to get better outcomes from programmatic advertising campaigns without adding more complexity.
Our algorithms help boost campaign performance through curated PMP deals. These deals are activated directly within Demand Side Platforms (DSPs) and continuously optimised to help clients beat their campaign benchmarks.
We work with enterprise and mid-market advertisers globally, deploying our technology around their requirements. Our product is already in active use, so you’ll be shipping to a live environment, not a throwaway prototype.
We’re looking for a Full-Stack Engineer who wants to help us push the boundaries of supply-side optimisation and play an important role in developing the technology behind Kertoa.
We believe in high standards, hard work, and delivering results. If that resonates, you’ll feel at home here.
The role
We are hiring a full-stack engineer to join a small team and own features end to end: interface, API, data, and third-party integrations. Day to day that is React, Python, and MongoDB.
You will work across the product, not in a frontend-only or backend-only lane. Business rules must stay consistent from the UI through to external systems. When something looks right on screen but wrong downstream, you will debug it.
What you will do
Design, build, and ship product features across UI and API
Integrate with external vendors and keep those integrations reliable
Add tests with your changes and help verify work in a shared environment
Improve quality: access control, validation, error handling, operational tooling
Collaborate with product and QA; hand off work with evidence, not “should work”
Learn the domain on the job, advertising experience is useful, not required
What we look forRequired
Proven full-stack delivery: you have shipped UI and API together
React, Python, and MongoDB (or very close equivalents and a willingness to work in this stack)
Experience calling third-party APIs (auth, retries, awkward vendor behaviour)
Tests as a normal part of shipping
Clear written communication
Ability to work in an existing codebase and match established patterns
Strong plus
B2B / ops / workflow products
Multi-tenant access control
Browser-level testing against a shared environment
Small-team or early-stage experience
Advertising or media technology (nice, not required)
How we work
Smallest correct change; no drive-by rewrites
Features include tests
Work that touches an external vendor is done when it is deployed and confirmed in that vendor’s system, not only in our app
We do not use live customer records for development
What this role is not
Not a design-system or pixel-only frontend role
Not a backend-only role with no UI
Not a greenfield rewrite, you will extend a working product
Not a large on-call organisation; it is a small team with real vendor side effects
Role Details
Type: Full-time (contract considered)
Location: Remote (UK timezone overlap preferred)
Reports to: Engineering / founding team

Work arrangement
Yes