Lead JavaScript Engineer

About VWO

VWO is a leading Digital Experience Optimization platform trusted by over 3,000 businesses in 100+ countries, including global brands like Samsung, Vodafone, Toyota, HBO, and Domino's. What began 15 years ago as one of the world’s first A/B testing tools has since evolved into a comprehensive, enterprise-grade platform used by product, marketing, and growth teams to experiment, personalize, analyze behavior, and build exceptional digital experiences.

Today, VWO offers a full-stack suite for A/B testing, multivariate testing, feature rollouts, heatmaps, session recordings, behavioural analytics, surveys, personalization, and more across web, mobile, and server-side applications — all in one unified platform. We enable teams to make confident, data-driven decisions that drive user engagement, retention, and conversion.

VWO is a profitable, founder-led business with $50M+ ARR, strong EBITDA margins, and a history of capital-efficient, sustainable growth. In January 2025, Everstone Capital acquired a majority stake in the company to help accelerate our global expansion — both organically and inorganically.

We are a fully remote team of 450+ people, with go-to-market teams across the Americas, Europe, and APAC, and product and engineering anchored in India. Our culture values deep thinking, fast execution, and strong ownership — with minimal bureaucracy and high autonomy. Despite our scale, we continue to operate with the agility and ambition of a startup.

As a Lead JavaScript Engineer, you will be required to work on various JavaScript libraries that are served on our customers’ websites thereby impacting millions of users. These libraries are the core of all the features of VWO.

We love vanilla JavaScript and work with cutting-edge technologies like TypeScript, Rollup.js, Cypress, and ESLint.

We are obsessed with Web Performance. See some of the improvements that we did https://engineering.wingify.com/posts/performance-improvements-in-vwo-smart-code/

What You’ll Do:

• Develop and maintain core JavaScript libraries used across our products.
• Own the architecture, development, and maintenance of our core JavaScript libraries.
• Build reusable, modular code to be shared across various JavaScript projects.
• Review code, mentor peers, and set coding standards and best practices for the team.
• Collaborate with Product and Engineering teams to implement features that deliver real value to customers.
• Lead efforts to optimize for speed, size, and reliability—web performance is at the heart of everything we do.
• Write thorough unit and integration tests to ensure cross-browser compatibility and regression-free deployments.
• Contribute to the open-source community by sharing insights, writing blog posts, and participating in discussions about the technologies we use.

What You’ll Bring:

• 5–8 years of experience in JavaScript development, with at least 1–2 years in a lead or senior role.
• Deep expertise in Vanilla JavaScript, with a strong grasp of the browser environment, DOM, and JavaScript APIs.
• Solid experience with TypeScript, HTML, and CSS.
• Comfort with using AI tools to boost productivity and code quality — AI-assisted development is a core expectation in this role.
• Proficiency in build tools and workflows like Rollup.js, ESLint, and modern JavaScript bundling strategies.
• Passion for web performance and a deep understanding of how browsers work under the hood (rendering, layout, events, caching, etc.).
• Strong debugging skills and experience with automated testing frameworks (we use Cypress).
• Experience writing cross-browser compatible code, including support for older browsers where needed.
• Familiarity with advanced JavaScript concepts: Promises, async/await, modularity, data binding, etc.
• A continuous learner who stays up to date with the latest trends and best practices in front-end development.

Why Join Us?

• You’ll work on high-impact products used by global brands and millions of users.
• You’ll be part of a passionate team that truly cares about code quality, performance, and developer experience.
• We foster a transparent, performance-oriented culture with plenty of room for learning and experimentation.

Location: Fully Remote