Top Front End Developer Jobs in Philadelphia, PA

Design and implement frontend applications using JS, CSS, React, and Flutter. Collaborate on technical specs and contribute to documentation, ensuring user experience and performance.

Design and develop web applications, mentor teammates, shape architectural decisions, write clean code, conduct testing, and troubleshoot issues.

Develop user-facing features using Vue.js, collaborate with back-end engineers, optimize performance, maintain code quality, and stay updated on blockchain trends.

Build and own WebGL and Three.js front-end experiences, including scene architecture, motion, visual design, performance, and accessibility. Prototype and validate products with users, use AI tools such as Cursor and Claude Code, and create reusable development patterns. Collaborate directly with company leadership, communicate technical constraints clearly, and progressively contribute across the full stack using Node, SQL, SST, and Drizzle.

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.

The Front End Developer will create and manage web design and digital marketing projects, requiring proficiency in HTML, CSS, and JS; experience with client interaction and ecommerce platforms is a plus.

Build and maintain intuitive frontend web applications for data upload, search, visualization, and interactive 2D/3D geospatial tools. Collaborate with scientists to design complex visualizations, modernize the frontend stack, mentor junior developers, and implement automated UI testing and deployment pipelines.

Own the AMS frontend, designing and shipping React and TypeScript features for data-intensive grids, forms, dashboards, and widgets. Integrate RESTful APIs using TanStack Query, manage state with React Context or Zustand, implement SurveyJS forms, and optimize performance for large datasets. Collaborate with backend engineers and designers, contribute to code reviews and Agile ceremonies, and work across time zones with an Australia-based team. The role requires US citizenship and willingness to pursue future security clearance.

Assist with marketing campaigns including website, landing page, email, and report design. Take ownership of projects, iterate quickly in a startup environment, apply front-end skills (HTML/CSS/C#/WordPress/PHP), and collaborate across the small team. Opportunity may convert to full-time.

Develop secure, data-rich frontend features using React and TypeScript for a DoD mission-planning platform. Integrate UIs with backend APIs, support map-based and AI-enabled decision-support workflows, write unit/integration tests, participate in code reviews and security remediation, and collaborate with cross-functional teams with periodic onsite sprint planning in Laurel, MD.

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.

Develop mobile-first, responsive Vue.js frontends focused on performance and UX. Build frontend management systems, participate in code reviews and team ceremonies, mentor junior engineers, and collaborate with backend teams.

The Frontend Engineer will develop user interfaces utilizing React and other technologies to enhance community knowledge organization and data interaction.

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 and maintain responsive, accessible, high-performance frontend applications using modern frameworks. Contribute to greenfield and legacy modernization, follow code quality best practices, leverage AI-assisted tools and LLM prompting, collaborate with product, design, and backend teams, and ensure reusable components, cross-browser compatibility, and performance optimization.

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.

Build and maintain Plane's local-first browser client surfaces: large, virtualized workspaces, collaborative editor, offline/caching layers, and shared design-system components. Work cross-functionally with designers and backend engineers, extend sync and conflict-resolution behavior, optimize rendering performance, and triage cross-browser and self-hosted issues.

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.

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.