> Markdown version of [/jobs/ext/4669924-senior-frontend-engineer](https://www.wearedevelopers.com/jobs/ext/4669924-senior-frontend-engineer). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Senior Frontend Engineer - **Company:** MOBI AI LLC - **Location:** Somerville, MA, United States - **Experience:** Expert - **Salary:** $140,000 - $190,000 - **Contract:** Permanent contract - **Skills:** JavaScript (Programming Language), Artificial Intelligence, HTML5, Browser Compatibility, Cascading Style Sheets (CSS), Software Quality, Software Debugging, Design of User Interfaces, Human-Computer Interaction, E2e Testing, Responsive Web Design, Screen Reader, Data Streaming, Systems Integration, TypeScript, Model-Driven Development, ReactJS, Cypress (Programming Language), AI Coding Agents, Backend, Git, Webpack, Information Technology, Playwright, Build Tools, Codebase, Front End Software Development, Restful APIs, Model Context Protocol, Es2015, Code Restructuring, Software Version Control, Api Management - **Published:** November 11, 2026 - **Apply:** https://www.careerbuilder.com/job-details/senior-frontend-engineer-somerville-ma--f00c3c49-d2ac-4540-95c5-0b482f26779a ## About the Role User Interface/Experience (UI/UX), Artificial Intelligence (AI), Power Generation, System Integration (SI), Team Building, Team Lead/Manager, Communication Skills, Business Growth, Customer Relations, Production Support, AI-assisted software development is essential to this role. You should be able to show how you use coding assistants and agents to implement, test, debug, and refine changes across an existing codebase, through professional or substantive project work. You remain accountable for the result: understanding the code, checking assumptions, and independently verifying correctness, security, accessibility, and maintainability., * Bachelor's degree in Computer Science, Engineering, or related field-or equivalent practical experience. * Proficiency in HTML5, CSS3, JavaScript (ES6+). * Deep practical experience with React, including component architecture, state management, and diagnosing rendering and performance issues. * Strong practical TypeScript skills, including type-safe component and API contracts and the ability to work confidently in an existing codebase. * Experience writing and maintaining reliable automated frontend tests with tools such as Playwright, Jest, or Cypress, including asynchronous behavior and failure cases. * Demonstrated proficiency with AI coding assistants and agents, shown through professional or substantive project work that you can explain, test, and critically review. * Experience directing AI tools through changes across multiple files in an existing codebase, including implementation, test generation, debugging, and refactoring. * Strong judgment in evaluating AI-generated solutions: able to explain the code, verify its behavior, identify errors, and recognize when independent investigation or a different approach is needed. * Experience integrating frontend applications with RESTful APIs and asynchronous services, including authentication, session state, and error recovery. * Understanding of responsive design principles and cross-browser compatibility. * Experience with build tools and version control (e.g., Next, Vite, Git). * Evidence of independently shipping and supporting complex frontend features, explaining design tradeoffs, and collaborating effectively with designers, customers, and engineers. * Preferred: Experience shipping AI-powered user interfaces. * Bonus: Understanding of MCP and response streaming. ## Description As a Senior Frontend Engineer at Mobi, you'll own customer-facing features from defining the problem and making design trade-offs to implementation, release, and production support. We're looking for a curious engineer who can turn ambiguous customer needs into reliable, accessible experiences for AI-powered travel. You'll build interactive search and recommendation experiences, virtual concierge services, and data-rich dashboards. You'll work directly with clients, designers, backend engineers, and AI engineers to scope solutions, explain trade-offs, and iterate on what users need. You'll build tool-driven interfaces for AI assistants and app integrations, including Model Context Protocol (MCP) apps. The work includes streaming and partial results, authentication and session continuity, and clear loading, error, and confirmation states., * Design, build, and maintain production React and TypeScript applications, making explicit trade-offs in component architecture, state management, and maintainability. * Turn designs and prototypes into responsive, accessible interfaces, including keyboard navigation, screen reader support, and usable pending, error, and confirmation states. * Use AI coding assistants and agents throughout the development lifecycle to accelerate delivery while maintaining high standards for correctness, accessibility, performance, and maintainability. * Work with design, backend, and AI engineers to define UI contracts for tool calls, streaming, session state, and recoverable failures. * Measure and improve frontend performance, including responsiveness, rendering, and the user experience during slow or interrupted requests. * Stay current with front-end trends, tools, and emerging AI technologies. * Debug production issues across browser rendering, application state, and API integration; use telemetry and reproducible cases to find root causes and prevent regressions. * Build and maintain deterministic unit, component, integration, and end-to-end tests for UI behavior and API contracts. Partner with AI and backend engineers on scenario-based evaluation of model-driven interactions, including partial results, failures, and user confirmations. * Develop and share effective AI-assisted workflows to improve engineering productivity and code quality.