TypeScript Engineer, JS Agent

What you’ll do

• Build and maintain our browser-side TypeScript/JavaScript agent used for device identification, bot detection, and risk assessment
• Engineer for stealth, resilience, and performance-minimizing footprint, resisting detection, and maintaining compatibility across browsers
• Stay ahead of browser changes, plugin behaviors, and fingerprinting techniques
• Collaborate with backend, security, and data science teams to align signal capture with detection logic
• Write comprehensive tests and contribute to CI pipelines that ensure functionality across a wide range of platforms and devices
• Contribute to a widely-used open-source project with 27K+ GitHub stars and 25B+ monthly usages
• Use native browser JavaScript APIs (we use ZERO third-party libraries in runtime)
• Push TypeScript and other tools to their limit

What You Bring

• 3-5 years of JavaScript and TypeScript experience, especially in browser environments
• Experience building libraries or SDKs, especially for production or developer-facing use cases
• Strong frontend experience (~80%), with backend familiarity (~20%)
• Deep knowledge of browser JavaScript APIs
• Experience of writing asynchronous code with parallel execution
• General understanding of the HTTP protocol and web security
• Proficiency with build tools like Vite, Webpack, Rollup, Esbuild, including code obfuscation and minification
• Experience with modern testing frameworks such as Vitest, Jasmine, Jest, or similar
• Familiarity with security principles, privacy best practices, and adversarial engineering
• Comfortable working in fast-paced environments without rigid specifications
• Strong sense of ownership and autonomy; you enjoy working independently and solving hard technical problems
• Clear written and verbal communication skills in English

Nice to Have

• Experience in complex domains like media, gamedev, or security, or on technically demanding browser projects (e.g. Google Docs, Figma, Miro, or 3D browser games)
• Contributions to open-source projects, especially in the JavaScript/TypeScript ecosystem
• Historical record of open source contributions

Compensation Range

For US-based employees, the cash compensation range for this role is $130,000 – $180,000.