Senior Frontend Software Engineer (JS, TS, browser APIs) Offline

Project Description

Our client provides a human insight platform that allows organizations to gather feedback from real users interacting with their products.

We’re looking for a Senior Frontend Software Engineer with strong expertise in JavaScript, TypeScript, and browser APIs, to help drive the development of our browser extension used by participants across our research platform. This is a hands-on role focused on Manifest V3 WebExtensions, requiring experience with media APIs, cross-browser behavior (Chrome and Firefox), and a mindset for building resilient, privacy-aware client-side code.

Job Description

• 6–8+ years of frontend development experience
• Deep knowledge of JavaScript and TypeScript
• Solid experience with WebExtensions API (Manifest V3), especially service_worker, runtime, tabs, webNavigation, storage, and scripting
• Experience working with Lit and React
• Hands-on use of media APIs such as getUserMedia, getDisplayMedia, MediaRecorder, etc.
• Understanding of browser behavior differences, especially between Chrome and Firefox
• Experience debugging browser extension issues and handling edge cases related to permissions and tab lifecycle
• Good sense of usability and performance in constrained environments (browser extensions)
• Proven ability to work independently in scoped initiatives with tight constraints
• Clear written and verbal communication in English

Job Responsibilities

• Design and implement new features in our Manifest V3 WebExtension, with a strong focus on performance, maintainability, and security
• Handle media capture, tab management, and runtime messaging logic across browser contexts
• Collaborate with other engineers and product stakeholders to define technical approaches
• Ensure cross-browser compatibility and graceful fallbacks for unsupported features
• Write reliable, well-documented code with meaningful test coverage
• Participate in code reviews, demos, and technical discussions with a focus on pragmatic decisions and shared understanding
• Identify opportunities to simplify scope or streamline implementation without sacrificing quality