Senior Software Engineer - Client Services

This role fits a Middle/Senior Frontend (UI) Developer with 5+ years of experience in building and customizing web interfaces for client campaigns. You need strong skills in JavaScript, jQuery, HTML, CSS, and basic design tools like Photoshop, plus experience with A/B testing and marketing platforms. The candidate should be familiar with developing dynamic website variations, working on experimentation setups, and delivering client-focused UI solutions in fast-paced environments.

1. How would you implement A/B testing campaigns using JavaScript and jQuery on a platform like VWO?
   I would dynamically modify the DOM based on experiment variants, ensure proper event tracking, and maintain separation between control and variation logic. Clean, modular scripts help manage multiple experiments efficiently.

2. What challenges do you face when injecting frontend changes into existing client websites?
   Conflicts with existing styles/scripts, inconsistent DOM structures, and performance issues are common. I handle them by writing scoped CSS/JS and thoroughly testing across environments.

3. How do you ensure cross-browser compatibility when working with HTML, CSS, and JavaScript?
   I follow standard-compliant code, use fallbacks where necessary, and test across major browsers. Tools and polyfills help address compatibility gaps.

4. What are best practices when writing jQuery for production-level applications?
   Avoid excessive DOM manipulation, cache selectors, and keep logic modular. Even with jQuery, maintain clean and maintainable code structure.

5. How do you translate design mockups (e.g., from Photoshop) into pixel-perfect web pages?
   I carefully inspect spacing, typography, and layout details, and implement responsive designs using CSS. Iterative QA ensures visual accuracy.

6. What performance considerations are important when building marketing campaign pages?
   Fast load times, minimal DOM manipulation, and optimized assets are critical. Lightweight scripts and efficient CSS improve user experience.

7. How do you debug issues in live client campaigns?
   I use browser dev tools to inspect DOM, network, and console logs, reproduce issues, and isolate conflicts with existing site code before applying fixes.

8. What is your approach to writing maintainable HTML and CSS for dynamic campaigns?
   I use semantic HTML, modular CSS (BEM or similar), and keep styles scoped to avoid conflicts. Readability and structure are key.

9. How do you manage multiple concurrent client projects effectively?
   I prioritize tasks, break work into smaller deliverables, and maintain clear communication with stakeholders. Time management is crucial in fast-paced environments.

10. What role does UX play in A/B testing and campaign development?
    UX is central—small design or interaction changes can significantly impact conversion rates. I focus on clarity, usability, and measurable improvements.

Wingify is a leading experimentation and conversion optimization company behind VWO, helping businesses improve digital experiences through A/B testing and personalization. They are hiring a Senior Software Engineer (UI Developer) to design and build client-facing campaigns using HTML, CSS, JavaScript, and jQuery, with a focus on experimentation, performance, and visual quality. This is a full-time role requiring 5–8 years of experience, strong frontend fundamentals, and design skills including Photoshop. It’s a great opportunity to work on high-impact optimization projects, directly influencing user behavior and business outcomes for global clients.