Senior React Platform Engineer

Mattermost is the leading collaborative workflow platform for defense, intelligence, security, and critical infrastructure. They are seeking a Senior React Platform Engineer to lead the evolution of their web architecture and ensure high performance and reliability of their web platform.

Responsibilities:

• Implement secure communication features and real-time messaging capabilities optimized for high-latency or disrupted network conditions
• Optimize web application performance, including bundle size, initial load time, runtime memory usage, and asset delivery pipelines
• Design and maintain shared React component libraries and architectural patterns to ensure platform-wide consistency and scalability
• Collaborate with backend engineers to integrate web apps with APIs and ensure smooth data synchronization under constrained or intermittent network environments
• Contribute to Mattermost's open-source React codebase, sharing platform-level and resilience-focused solutions with the broader developer community
• Work with product managers and designers to translate user requirements into technical solutions and prototypes, with a focus on graceful degradation and resilience
• Implement comprehensive testing strategies including unit tests and automated end-to-end testing (e.g., Cypress or Playwright) under simulated network stress
• Debug and resolve web-specific issues across different browsers, platforms, and operating system versions
• Participate in code reviews and provide mentorship to colleagues on React best practices, platform standards, and resilient architecture
• Proactively master and integrate the latest advancements in AI and LLM-powered development tools (e.g., Cursor, Claude, GitHub Copilot) to accelerate engineering velocity, automate repetitive platform tasks, and establish best-in-class AI-assisted workflows

Requirements:

• BS in Computer Science, Computer Engineering, or related field/experience
• 5+ years of professional experience developing mobile applications with React
• Strong proficiency in JavaScript/TypeScript and React ecosystem including hooks, state management, and component architecture
• Deep understanding of Browser Networking (WebSockets, HTTP/2) and how to architect applications for high-latency, packet loss, or unstable connections
• Proficiency with AI/LLM tools to improve and accelerate development
• Experience with state management libraries (Redux, Zustand, or similar) and async data handling
• Familiarity with web app testing frameworks and debugging tools for React applications
• Strong problem-solving skills and ability to work independently in a remote, distributed team environment
• Excellent written and verbal communication skills for collaborating across time zones
• For candidates residing in the U.S.: This role may require the ability to obtain and maintain a U.S. government security clearance in the future. As such, U.S. applicants must be U.S. citizens and eligible under applicable clearance requirements
• Applicants must meet eligibility requirements for access to export-controlled information as defined by U.S. export control laws, including EAR and ITAR
• Previous experience building end user products for enterprises or security-focused users
• Contributions to open-source projects
• Knowledge of accessibility standards and implementing inclusive web experiences
• Has worked fully remotely with global teams
• Expertise in defense, intelligence, or security-focused workflows