Senior Web Developer (Growth & Conversion Optimization)

Clay Labs•New York, NY

About The Position

Our mission is to help organizations turn any growth idea into reality. We see growth as a creative practice, not a formula. Finding and reaching your best-fit customers takes unique ideas and constant iteration. As AI makes execution faster and tactics easier to copy, creativity is the only lasting advantage. We're already helping thousands of customers — including Anthropic, Notion, Google, and Ramp — go to market with unique data, signals, and AI research. In 2025, we raised a $100M Series C backed by world-class investors including Sequoia, CapitalG, and First Round — and crossed $100M in revenue. In 2026, we announced our second employee tender offer in 9 months at a new $5B valuation. We also launched a community equity round, for our customers, agency partners, and club members. Some things to know about us: Our community includes 11,000+ customers, 150+ integration partners, 125+ agencies, 50+ Clay clubs, and 30k members on Slack. Our culture is unique inside and outside of work. Our team members are also DJs, activists, writers, clowns, marathoners, skydivers, psychedelic therapists, social workers, and more. All employees can work for free with world-class coaches who specialize in creativity, management, and more. Our operating principles — including negative maintenance and non-attached action — guide our work. Read more about them here. Read about us in the NYT, Forbes, First Round Review, and more. Hear from our employees directly on our Glassdoor page! Senior Web Developer (Growth & Conversion Optimization) What You'll Do Build high-converting web experiences in Webflow. You'll own the development of landing pages, conversion funnels, and website features from concept through launch. This includes writing custom JavaScript for interactive elements, building CMS architectures, and pushing Webflow to its limits with advanced functionality. You'll ship quickly with a fast launch cadence, moving from brief to production-ready code without heavy handoffs. Develop the technical infrastructure that powers growth. You'll architect and implement the integrations, APIs, webhooks, and automation that connect our web properties to the broader marketing and sales stack. This means building custom middleware, debugging complex integration issues, implementing event tracking architectures, and ensuring data flows seamlessly between Webflow, our CRM, analytics platforms, and marketing automation tools. You'll write production-grade code that's maintainable, scalable, and built to last. Own conversion optimization through code. You'll design and implement A/B testing frameworks, experimentation infrastructure, and personalization engines that enable systematic improvement of conversion rates. You'll analyze funnel data to identify bottlenecks, translate insights into technical solutions, and build features that reduce friction and drive measurable improvements in key metrics. Ship with technical excellence and collaborator. You'll balance speed with quality, knowing when to refactor and when to iterate. You make strong technical decisions under pressure, keep stakeholders informed without slowing down, and refine based on real performance data and conversion metrics. You're opinionated about code quality, web performance, and best practices, but pragmatic about shipping. Collaborate to translate business goals into technical solutions. You'll partner closely with Marketing, Product, and Growth teams to understand objectives and build the technical solutions that deliver results. You're comfortable leading development projects, providing technical guidance to stakeholders, and supporting new initiatives through launch. You translate non-technical requirements into clean, efficient code. Push technical boundaries while maintaining reliability. You'll explore new ways to create standout web experiences—whether that's implementing advanced animations with GSAP, building interactive elements with Three.js, or creating dynamic personalization systems. But you never sacrifice performance, accessibility, or conversion for flashy features. Every technical decision serves the user experience and business goals.

Requirements

5+ years of professional web development experience, with at least 3 years building conversion-focused websites and landing pages
Expert-level Webflow development skills, including advanced CMS implementations, custom code integration, and complex builds that push the platform's capabilities
Strong programming fundamentals in JavaScript/TypeScript, HTML5, and CSS3. You write clean, maintainable code that other developers can understand and build upon
API integration expertise—comfortable building REST API clients, implementing webhooks, handling OAuth flows, and debugging integration issues. You've connected web properties to CRMs, marketing automation platforms, and analytics tools
Experience with modern web development tools and frameworks: Git version control, Node.js, React (or similar), serverless functions, and build tools. Familiarity with Three.js, GSAP, and animation libraries is a plus
A proven track record of improving conversion rates through technical implementation of tests, optimizations, and experiments. You understand A/B testing methodology, statistical significance, and CRO best practices
Web performance obsession—you optimize for Core Web Vitals, write efficient code, and know how to make websites fast. You've debugged performance issues and shipped measurable improvements
A portfolio demonstrating exceptional development skills: Live websites you've built, complex functionality you've implemented, and projects where you owned the technical execution end-to-end. Include code samples or GitHub repositories
A systems mindset for building scalable, maintainable codebases and reusable components, with the flexibility to move fast when needed
Strong collaboration and communication skills—you keep stakeholders informed, explain technical concepts clearly to non-technical teams, and work effectively across functions
Analytical thinking paired with business acumen. You understand how your code impacts conversion metrics, user behavior, and revenue
The ability to work autonomously, taking projects from requirements through deployment without constant oversight, while keeping teams aligned
A get-it-done attitude with high standards. You ship, you iterate, you improve

Nice To Haves

Experience with analytics platforms (GA4, Segment, Mixpanel) and implementing custom tracking
Backend development experience or full-stack capabilities
Understanding of technical SEO and search optimization
Previous experience in high-growth startups or fast-paced environments
Contributions to open-source projects or technical writing