Software Engineer - Client Services (CSS, Vanilla JS)

We are looking for a Senior Software Engineer who is comfortable working with Vanilla JavaScript, HTML, and CSS to build and customize frontend solutions, debug complex client-side issues using browser developer tools, and handle DOM manipulation, event handling, and dynamic UI updates. Should be confident analyzing APIs through Fetch/XHR requests, tracking DOM changes using MutationObserver and browser console techniques, and making real-time UI modifications using inspect element and custom scripts. The role also requires troubleshooting frontend issues across browsers and collaborating with cross-functional teams to solve real-world client scenarios while ensuring smooth and optimized user experiences., Examples of Tasks You Will Perform

• Rearranging elements on a page dynamically.
• Creating new UI blocks using JavaScript, jQuery and CSS.
• Overriding existing styles safely.
• Preventing interference from existing scripts and styles.
• Ensuring compatibility across devices and screen sizes.
• Making changes that survive dynamic DOM updates.
• Tracking user interactions for experiments.

• Strong understanding of Vanilla JavaScript, jQuery, HTML and CSS.
• Advanced DOM traversal and manipulation.
• Event handling and debugging in live environments.
• Using MutationObservers for dynamic content.
• Handling Single Page Applications (SPAs).
• Writing safe and conflict-free CSS.
• Understanding browser behaviour and edge cases.
• Performance-safe scripting on production websites.

Important Mindset Difference

This role is highly problem-solving oriented. There is no clean HTML, no reusable components. You must analyse the DOM like a detective and figure out how to safely manipulate it in real-time.

Who Will Enjoy This Role

• Developers who love JavaScript, jQuery and CSS deeply.
• Those who enjoy solving DOM challenges.
• People are comfortable working without access to source code.
• Developers who like debugging tricky real-world issues.

We don't build websites - we intelligently manipulate the DOM using Vanilla JavaScript, jQuery and CSS to run experiments on live websites.

Wingify is a remote-first company with more than $100M in revenue, serving over 4,000 customers worldwide, supported by a team of nearly 800 talented people across 11 global offices.