We are looking for a highly experienced, hands-on Lead CRO Developer to build and deliver A/B and multivariate experiments across our client accounts. This is fundamentally a development role. The majority of the role is hands-on coding, implementation, QA and troubleshooting of experiments, not CRO strategy, programme management, or roadmap ownership.
You will take test designs and specifications and turn them into robust, production-ready experiments across enterprise experimentation platforms. As the lead developer, you will also act as the technical escalation point for complex builds and help maintain high development and QA standards, while remaining deeply hands-on day to day.
JavaScript: Advanced JavaScript (ES6+) skills. You must be comfortable writing substantial custom code for experiments rather than relying on visual editors.
HTML & CSS: Strong HTML5 and CSS3 development skills, including responsive implementation and accurate translation of supplied designs.
Optimizely: Strong hands-on experience building experiments in Optimizely Web. Experience with Optimizely Full Stack / Feature Experimentation is highly valuable.
Experimentation development: Extensive experience personally building and shipping A/B and multivariate tests in live ecommerce or enterprise environments.
React / Next.js: Strong experience developing and debugging experiments on React and Next.js applications, including SPAs.
QA & debugging: Excellent browser developer-tools skills, troubleshooting ability and rigorous cross-browser/device experiment QA.
Tracking & tag management: Experience with GTM and/or Tealium, event tracking and data layers as they relate to experimentation.
Cross-platform delivery: Ability to work confidently across different CMSs, ecommerce platforms, and proprietary client technology stacks.
We are particularly interested in developers with hands-on build experience across several of the following. Depth of practical development experience is more important than simply having used the platform.
You will not be expected to own the CRO roadmap, hypothesis strategy, or wider department. 'Lead' reflects the level of technical capability we need: someone who can take on the most complex experiment builds, make sound implementation decisions, solve difficult development problems, review code where required and act as the technical point of escalation for CRO development.
Why Biglight?
Biglight is an experience design agency focused on helping leading B2C and B2B brands create remarkable customer experiences that drive commercial impact.
We combine UX, design, insight, and experimentation to unlock new value for our clients — including organisations like The North Face, George @ ASDA, M&S and Booker Cash N Carry.
We are a people business, powered by talented specialists who want to make a difference. We hire the best people, regardless of background, and create an environment where they can grow while delivering exceptional work for our clients.
Read more about us at https://biglight.co.uk/
We are committed to fostering a diverse and inclusive workplace where everyone feels respected, valued, and empowered to contribute their authentic selves.
From discovery and strategy to creative exploration and execution, we help our clients achieve their bold commercial ambitions.
Our clients include D2C brands such as adidas, Timberland, The North Face and Vans, retailers such as Asda, Hobbycraft and M&S and B2B businesses including LKQ, Booker, Brakes and Magnet.
