Top Senior Front End Developer Jobs in Denver & Boulder, CO

Lead end-to-end implementation of high-fidelity, performant, and accessible frontend features for a realtime collaborative visual canvas. Translate designs into polished interactions, optimize performance and accessibility, collaborate with PMs, designers, and backend engineers, and shape frontend best practices and design systems.

Lead frontend architecture and technical strategy for a collaborative work platform. Build scalable React/TypeScript applications, design systems, real-time collaboration (sync, offline, serialization), optimize performance and observability, mentor engineers, and collaborate with Product, Design, and Backend teams to deliver high-quality, maintainable user experiences.

Lead technical direction and contribute to the frontend codebase, building user-facing tools and mentoring team engineers to enhance user experiences.

Develop and maintain web application user interfaces using Vaadin and front-end technologies. Apply UI fundamentals (including Fitts' law), refactor enterprise applications, collaborate with clients, and mentor/train other front-end developers.

Design, develop, and support web application front-ends and UX using HTML/CSS/JavaScript. Collaborate with clients and teams in Agile environments, perform UX tasks (wireframes, prototypes, usability), ensure responsive cross-browser/device compatibility, mentor peers, and provide design support across projects and corporate communications.

Build and maintain responsive, high-performance user-facing React/Next.js applications for privacy-focused web3 products. Collaborate with backend engineers, identify and fix performance bottlenecks, participate across the product lifecycle, write tested production-quality code, and iterate quickly on UX and developer-facing frameworks.

Build and maintain the company website, client-facing portal, and internal web apps. Design and structure web pages, implement UI enhancements, optimize performance and scalability, collaborate with backend engineers (Go), ensure brand-consistent design, and mentor teammates to drive product excellence.

Founding-team senior engineer to architect and build core platform components. Work with CEO/CTO to develop scalable distributed backend systems and frontend using React, Node.js and TypeScript. Implement solid coding practices, testing, CI/CD, and agile workflows while iterating rapidly in an early-stage fintech startup.

Own and evolve the front-end architecture for a high-throughput, real-time trading app using Next.js, React, and TypeScript. Build pixel-accurate, accessible, responsive UIs under strict performance budgets; optimize rendering, state management, data flow, and bundle size for sub-second interactions. Integrate with REST and WebSocket APIs, lead end-to-end feature development, set engineering standards, mentor engineers, and contribute across the stack when needed.

Early-stage frontend-focused product engineer to own web and mobile experiences (React, React Native, Expo). Design conversational AI-native interfaces for financial planning, build in TypeScript across stack, define frontend architecture and component system, use agentic engineering tools, contribute to multi-model AI orchestration, and iterate quickly with founders and users.

As a Senior Frontend Engineer, you'll build and maintain a fraud prevention platform UI using ReactJS, collaborating with backend teams and ensuring code quality through tests and CI/CD processes.

Design and implement developer-facing UI from Figma to production using Hotwire (Turbo + Stimulus) and ViewComponents. Own the dashboard, API playgrounds, docs, marketing site, and data visualization. Optimize performance and bundle size, maintain a coherent component system, and ship polished, production-ready front-end with tests and CI/CD.

The Senior Full Stack JavaScript Developer will build and maintain user interfaces using React and Next.js, integrate with Node.js backends, and guide other developers. Responsibilities include ensuring accessibility, performance, and reliability of features, engaging in code reviews, and collaborating closely with product teams.

As a Senior Software Engineer, lead design and development of core backend services while mentoring other engineers and enforcing best practices.

Lead frontend architecture and developer experience for a high-traffic React/TypeScript SPA. Maintain a reusable design system, enforce performance and type-safety standards, improve build/test/deployment tooling, mentor engineers, and partner cross-functionally to deliver reliable, well-tested features. Evaluate AI dev tools and research emerging frontend technologies.

The Sr/Staff Frontend Engineer will develop new web applications, enhance UI experiences, architect solutions, and collaborate with various stakeholders to ensure a scalable and secure platform.

Lead frontend modernization by migrating legacy web apps into a microfrontend ecosystem, ship production-critical React/Next.js code, define reusable platform patterns, and collaborate cross-functionally to ensure performance, developer experience, and long-term maintainability.

As a Senior Frontend Engineer, you will design and build web applications, owning major UI projects, collaborating with cross-functional teams, and optimizing performance for a seamless user experience.

The role involves designing and building internal web applications for Nebius, focusing on automating data center operations and developing user interfaces for infrastructure management.

Design and implement scalable frontend solutions using JavaScript/TypeScript and React. Drive architecture discussions, ship features with minimal guidance, maintain code quality and styling standards, collaborate across agile teams, ensure performance and scalability, and manage end-to-end feature lifecycles in a fast-moving environment.

Lead design, development, and maintenance of enterprise-grade React + TypeScript applications. Own front-end performance, responsiveness, and security; integrate with .NET/Azure backends; mentor junior developers; perform code reviews and debugging; modernize legacy apps; collaborate with designers, offshore teams, and stakeholders in Agile ceremonies.

Develop and maintain TypeScript/JavaScript-based web UIs and cloud-native microservices for mission management systems. Build front-end features (Vue 3), write automated tests, deploy via DevSecOps pipelines, troubleshoot bugs, and collaborate in agile teams in a secured SCIF environment requiring TS/SCI clearance.

Lead frontend development of production web applications using Svelte and other frameworks. Build reusable components, integrate REST/GraphQL APIs, ensure UI/UX quality, accessibility, and performance. Lead a small team, coordinate releases with QA, write tests, follow Git and CI/CD workflows, and collaborate remotely with stakeholders across the US.

Design and build performant, accessible frontend solutions across web apps, email campaigns, kiosks, and interactive experiences. Collaborate with UX and backend teams, write maintainable tested code, drive test automation and performance optimization, maintain codebases, and mentor junior engineers.

Develop and improve real-time drone tele-operations features, cloud-based products, and quickly prototype new front-end experiences while transitioning to a new tech stack.