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

Own frontend architecture for React and TypeScript applications supporting complex research and analytics workflows. Build performant, accessible interfaces; establish standards for performance, testing, accessibility, and CI quality gates; evolve shared component libraries and design systems; partner on API contracts; address technical debt; contribute to Django services; and mentor engineers while leading department-wide technical initiatives.

Leads the design and development of complex frontend systems and product features using Angular and React. Architects scalable frontend patterns, improves performance and engineering velocity, drives testing and code-quality practices, and leads major technical initiatives. Partners cross-functionally with backend, product, design, integrations, and QA; makes technical decisions, mentors engineers, and advances frontend architecture and collaboration across teams.

Build and improve ClickUp’s core product experiences using Angular and React. Responsibilities include architecting reusable frontend code, collaborating with product, design, backend, integrations, and QA teams, improving performance and usability, maintaining unit and integration tests, resolving complex bugs, following state-management patterns, and mentoring teammates in a fast-paced environment.

Build and maintain frontend components for Ether.fi’s consumer DeFi products. Collaborate with designers to translate Figma designs into polished user experiences, develop client-side transaction and fund-management integrations, ship high-quality code, uphold frontend security practices, and contribute to refactoring and engineering excellence.

Build and refine front-end experiences for web and mobile: onboarding, checkout, gallery features, design system and enterprise dashboard. Collaborate closely with designers and PMs, ship fast, maintain aesthetic quality, and iterate with user feedback using React, Next.js and TypeScript.

As a Senior Frontend Engineer at Cinch, you'll lead the modernization and performance optimization of React-based user interfaces, collaborate with cross-functional teams, and architect scalable UI systems with a focus on AI-driven experiences.

Own and build the JTX frontend across web and mobile: real-time order books, charts, order entry, positions, wallet/signing flows. Optimize for low-latency streaming data, performance, security, and cross-platform consistency while making long-term architectural decisions and shipping rapidly.

Develop and maintain cloud-native, data-rich front-end web applications using TypeScript/JavaScript and modern frameworks. Work in an agile team to implement UI features, integrate with REST/websocket backends, write automated tests, deploy via DevSecOps pipelines, troubleshoot bugs, and support user adoption in a secure SCIF environment.

Lead development of interactive React front-ends with Chakra UI and Mapbox, build data visualizations (Plotly/ApexCharts), optimize performance for large and real-time datasets, enforce front-end best practices, mentor engineers, and collaborate with product, design, and backend teams to deliver accessible, responsive interfaces.

The Front End Developer will build web applications using React, work with RESTful services, and handle authentication using SAML or JWT while collaborating in an agile environment.

Develop and maintain WordPress websites, create custom themes and plugins, ensure cross-browser compatibility, and optimize for SEO. Provide guidance on user experience and explore new technologies.

Build and maintain a polished web portal for a premium banking and travel rewards platform using React. Collaborate with designers and engineers on feature scope and product direction, participate in code and design reviews, write well-architected code, tests, and documentation, establish frontend architecture standards, and mentor team members. The role also involves database and API integrations in a fully remote startup environment.

Build and optimize high-volume web applications using .NET, Node, React and AWS; maintain and improve existing systems; troubleshoot bugs; perform code reviews; mentor junior engineers; participate in on-call rotation; and improve scalability and performance.

Design, build, and maintain scalable, responsive web applications using React and TypeScript. Create reusable UI components, implement end-to-end tests with Cypress, optimize performance, collaborate with product/design/backend teams, participate in code reviews, mentor junior engineers, and contribute to architecture and API integrations.

Build high-performance, real-time Angular frontends for AI-driven agent interfaces. Implement SSE/WebSockets streaming, complex state management with Signals/NgRx, visualizations of agent chain-of-thought, human-in-the-loop controls, performance optimizations, and collaborate with backend/AI engineers on API schemas.

Build high-performance, real-time Angular UIs for AI-driven agent workflows. Implement SSE/WebSocket streaming, complex state management (Signals/NgRx), observability dashboards, HITL controls, performance optimizations, and collaborate on API/JSON schema design with backend and AI engineers.

Design and implement high-performance Angular frontends for AI-driven interfaces: real-time SSE/WebSocket streaming, complex state with Signals/NgRx, Chain-of-Thought visualizations, human-in-the-loop controls, performance optimization, API schema collaboration, and testing.

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.

Develop and enhance user-facing features for an LLM observability platform using React and TypeScript. Build reusable components and front-end libraries, translate designs into performant UI code, optimize cross-device/browser performance, and collaborate with backend engineers and designers to improve usability.

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 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.