Senior Front End Developer - CRO/Optimisation

Job Title: Senior Front End Developer - CRO/Optimisation
Location: London - up to 2 days per week in the office (Reading, Manchester or Birmingham would also be considered)
Salary/Rate: £650 inside IR35
Start Date: 20/07/26

Company Introduction
We have an exciting opportunity now available with one of our sector-leading telecommunications clients! They are currently looking for a skilled Front End Developer with extensive CRO experience to join their team for a contract until the end of the year.

We are looking for an experienced Senior Optimisation Engineer to work in our Optimisation team to help build out the web UI campaigns for our new services and applications.

This is a role for an experienced Front End web application developer to optimise our current UI to achieve OKR's set by the business and improve our customer usage and enjoyment metrics. You will be a strong Front End coder with experience of working in experimentation, optimisation & personalisation. In this role you will be working with optimisation tools in an Agile squad, ultimately responsible for and further evolving the engineering quality, design, implementation, and operation of your product.

You will work with business partners, engineers, data scientists, and UX designers to design, implement, test, deliver, and document complex applications, tools, systems and services

The must haves:

• Strong experience developing A/B/MVT optimisation campaigns
• Excellent knowledge of Vanilla JavaScript, CSS/Sass, HTML, jQuery
• Front End development experience in either React or Angular framework could be an advantage
• Technical expertise in A/B testing platforms like Optimizely or similar such as Adobe Target etc.
• A passion for great online experience and an understanding of end-to-end user journeys and customer experience/CX
• Solid experience of website personalisation and audience targeting
• Solid experience of working with fully responsive websites and ability to deliver experiences for desktop and mobile devices
• Solid experience of working with/building experiments for SPAs
• Advanced understanding of Data analytics and Tag management systems (GTM) - integrations and custom event tracking

If you are interested in this opportunity, please apply now with your updated CV in Microsoft Word/PDF format.

Disclaimer
Notwithstanding any guidelines given to level of experience sought, we will consider candidates from outside this range if they can demonstrate the necessary competencies.
Square One is acting as both an employment agency and an employment business, and is an equal opportunities recruitment business. Square One embraces diversity and will treat everyone equally. Please see our website for our full diversity statement.