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

Lead frontend technical strategy for Affirm’s checkout decision orchestration systems. Design and architect scalable web applications, guide major technical initiatives, improve reliability and operational processes, establish engineering quality standards, collaborate with product, design, and analytics, and mentor engineers. The role focuses on building fast, clear, and reliable checkout experiences using modern declarative UI frameworks.

Build and maintain responsive, accessible web interfaces using React, HTML, CSS, and JavaScript/TypeScript. Integrate applications with REST APIs and back-end services, implement WebSocket features, optimize Core Web Vitals, and develop reusable design-system components. The role also involves Node.js tooling, cross-browser compatibility, code reviews, QA collaboration, and front-end testing.

Build and maintain responsive, accessible front-end interfaces using React, React Native, HTML, CSS, and Shopify. Apply UX/UI principles, collaborate with designers and multidisciplinary teams, provide clear technical feedback, and independently deliver high-quality work on complex technology or AI-related projects. Contractors complete output-based tasks and must meet weekly minimum submission requirements, with an expected start within 24–48 hours of onboarding.

Lead frontend feature releases and own user experience, performance, testing, and production health for a React and TypeScript dental practice management platform. Collaborate with backend engineers using Java Spring Boot, develop AI-powered interfaces, integrate AI tools such as Claude, participate in code reviews, improve team efficiency, and estimate development work for timely delivery.

Develop and maintain responsive Angular web applications using Angular 19+, Signals, Reactive Forms, and modular component architecture. Build complex forms, integrate REST APIs with RxJS, optimize change detection and performance, and create unit tests with Vitest or Jest. Collaborate with design, backend, and product teams, troubleshoot cross-browser issues, participate in code reviews, and follow modern front-end development practices.

Owns the design, development, security, performance, and scalability of Cerby’s cross-browser Manifest V3 extension. Builds React and TypeScript experiences across extension surfaces, manages service-worker synchronization and authentication workflows, and ensures secure credential handling. Responsibilities include dependency and supply-chain security, testing, observability, code reviews, mentoring, cross-functional collaboration, and production delivery in an agile remote environment. The role also promotes responsible AI-assisted development practices.

Design, develop, and enhance custom SAP Fiori/UI5 applications; configure Fiori Launchpad; integrate OData services; perform UI debugging, performance optimization, code reviews, unit testing, and documentation while collaborating with backend and functional teams.

Develop and maintain SAP Fiori applications using SAPUI5, Fiori elements, OData, and SAP BTP. Responsibilities include Fiori Launchpad configuration, reusable components, performance optimization, authentication, deployment to ABAP and BTP runtimes, backend collaboration, testing, accessibility validation, documentation, and post-go-live support.

Design, build, and optimize responsive, high-performance front-end interfaces for a Web3 DEX using modern JavaScript frameworks and TypeScript. Collaborate with designers, product, and back-end teams to integrate blockchain APIs and smart contracts, mentor junior developers, troubleshoot issues, and contribute to mobile-first/PWA development while ensuring scalability and maintainability.

Architect and build a high-performance trading platform for active traders. Develop responsive web interfaces integrating real-time market data, low-latency execution workflows, and advanced trading tools. Collaborate with cross-functional engineering teams on large-scale initiatives, emphasizing scalability, performance, API quality, maintainability, developer experience, and end-user usability.

Lead the evolution of Seeq’s frontend infrastructure, including React systems, component libraries, state management, styling architecture, and reusable application patterns. Drive large-scale refactors, improve developer experience, ensure accessibility and performance, evaluate open-source tools, and establish technical standards adopted across teams. Collaborate with designers, product teams, and engineers through architecture reviews, documentation, code reviews, mentoring, and cross-team delivery.

Own the frontend architecture and implementation of a greenfield legal technology product using React and TypeScript. Build complex, secure, role-aware workflows; establish component, state-management, routing, form, validation, accessibility, performance, and testing standards; integrate backend APIs and AI-enabled capabilities; and provide technical guidance to frontend developers.

Designs, develops, tests, deploys, operates, and maintains scalable full-stack software products. Builds React-based enterprise applications, writes production-ready code, performs code reviews, improves reliability and performance, integrates APIs, and follows security, compliance, accessibility, and DevOps practices. Collaborates across teams using agile methods, analyzes failures, prioritizes work, and contributes to technology transformation and continuous improvement.

Lead frontend engineering for large-scale React web applications. Architect application patterns, structure, libraries, and coding standards; build React applications end to end; conduct code reviews; mentor engineers; promote performance, scalability, and maintainability; and collaborate with designers, product managers, and technical and non-technical stakeholders.

Lead front-end engineering for enterprise transportation applications using React, TypeScript, and Material UI. Responsibilities include front-end architecture, reusable component development, accessibility, responsive design, API integration, SQL troubleshooting, testing, CI/CD, code reviews, mentoring, Agile planning, modernization, and production support. The role independently leads features from requirements through deployment while collaborating with designers, product owners, analysts, engineers, testers, DevSecOps teams, and government stakeholders.

Build the realtime, HIPAA-compliant messaging and collaboration frontend ('Pulse') that makes an AI colleague feel human. Implement complex interactive data visualizations, micro-interactions, and high-performance accessible interfaces. Work embedded with product and design, own UI quality, iterate on AI-driven specs, and deliver production frontend experiences clinicians will trust.

Design, build, and deliver front-end features with strong UX focus. Own technical design, coding, testing, deployment, and monitoring in a continuous delivery, microservices environment. Collaborate with Product, implement automated QA practices, and contribute to production deployments while practicing robust testing methodologies.

Design, build, deploy, and maintain secure, scalable Java and Spring Boot services for a multi-tenant ecommerce SaaS platform. Develop REST APIs, optimize MySQL databases, operate AWS workloads, and support CI/CD, observability, testing, and production systems. Contribute to architecture and technical decisions, mentor engineers, troubleshoot issues, and participate in on-call support while ensuring PCI DSS compliance and responsible use of AI-assisted development tools.

Lead frontend engineering for the DataLab product, developing scalable React and TypeScript interfaces for enterprise financial applications. Guide frontend architecture, component design, accessibility, performance, developer experience, and testing practices. Collaborate with product managers and backend engineers, mentor teammates, make technical decisions, and promote AI-assisted coding tools while maintaining high standards for security, quality, and maintainability.

Build and lead customer-facing eCommerce booking features using React, Next.js, and TypeScript. Own checkout, payments, scheduling, and partner booking flows; improve conversion, accessibility, performance, observability, and reliability. Integrate commerce and third-party services, develop automated tests, support frontend architecture, instrument experiments and analytics, and monitor production outcomes. Collaborate across Product, Design, Marketing, and Backend teams while mentoring junior engineers and contributing to shared components and API contracts.

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

Build and maintain fast, intuitive frontend applications for blockchain and Web3 products. Collaborate with product, design, and engineering teams; develop reusable components and frontend architecture; integrate wallets and smart-contract interactions; improve performance, reliability, and accessibility; participate in technical planning and code reviews; mentor other developers and establish frontend best practices.

Develop and enhance primarily front-end financial and benefits products using React, JavaScript, TypeScript, and Node.js. Build scalable web applications, APIs, integrations, and infrastructure; contribute to product requirements; write automated tests; troubleshoot production issues; and support secure, high-availability systems. Collaborate cross-functionally in an agile environment while working with databases and cloud technologies.

Develop responsive frontend applications for defense and national security missions using React and TypeScript. Build high-performance 2D and 3D geospatial visualizations, real-time data interfaces, and secure service integrations. Optimize applications for large datasets and constrained hardware, write automated tests, collaborate across disciplines, mentor engineers, and guide frontend architecture and technical direction.

Lead end-to-end development of modern frontend initiatives using React and Electron. Design scalable architecture, improve performance and test coverage, resolve production issues, influence technical decisions, and collaborate with Product, Design, and Backend teams. The role includes mentoring engineers, maintaining code quality, supporting observability and incident response, and building secure, high-quality customer-facing payment and form workflows.