Senior CRO Developer — Hands-on A/B & Multivariate Expert (Hybrid)

Biglight; Greater London; Hybrid; GBP 75,000 - 110,000; Full time

Benefits offered by this job

Competitive salary

Hybrid office/home working (office Tue

Thu)

Perkbox benefits

25 days annual leave

Career development opportunities

Diverse, inclusive workplace

Job summary

Biglight is seeking a highly experienced Lead CRO Developer to build and deliver A/B and multivariate experiments across client accounts. The role is hands‑on, focusing on coding, implementation, QA and troubleshooting rather than CRO strategy or roadmap ownership.

You will turn test designs into robust production experiments across platforms like Optimizely, VWO, AB Tasty, Convert, Monetate, and more, while advancing React/Next.js based experiences and server-side experiments where needed.

Qualifications

• Senior, hands-on CRO development focus.
• Extensive experience building A/B/multivariate tests for ecommerce/enterprise.
• Strong coding across JavaScript, HTML, CSS with robust QA.
• Experience with enterprise experimentation platforms.
• Proficient in React/Next.js SPAs and server-side tests.

Responsibilities

• Build A/B and multivariate experiments from concepts and specs.
• Write clean JavaScript (ES6+), HTML5 and CSS3 for experiment variations.
• Develop experiments in Optimizely Web and other platforms.
• Create experiments in React/Next.js environments (SPAs).
• Handle complex tests involving DOM, state, targeting, and journeys.
• Support server-side/SDK based experiments and feature flags where needed.
• Implement and validate tracking with GTM/Tealium; resolve platform issues.
• Review complex builds and mentor other CRO developers when needed.

Skills

Advanced JavaScript (ES6+)

HTML5

CSS3

React

Next.js

QA & debugging

GIT

Vanilla JavaScript

Tools

Optimizely Web

Optimizely Full Stack

VWO

AB Tasty

Convert

Monetate

Webtrends Optimize

GA4

Tealium

Job description

Biglight is seeking a highly experienced Lead CRO Developer to build and deliver A/B and multivariate experiments across client accounts. The role is hands‑on, focusing on coding, implementation, QA and troubleshooting rather than CRO strategy or roadmap ownership.

You will turn test designs into robust production experiments across platforms like Optimizely, VWO, AB Tasty, Convert, Monetate, and more, while advancing React/Next.js based experiences and server-side experiments where needed.