JavaScript Engineer
Fingerprint
- Location
- United States
- Job Type
- full-time
- Salary
- Unknown
- Posted
- July 18, 2025
Job Description
JavaScript Engineer
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
- Optimize for both code size and execution speed in complex, adversarial environments
- 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 24K+ GitHub stars and 25B+ monthly usages
What You Bring
- Expert-level JavaScript and TypeScript experience, especially in browser environments
- Deep understanding of browser APIs, DOM behavior, timing attacks, and anti-debugging techniques
- Experience building libraries or SDKs, especially for production or developer-facing use cases
- Strong frontend experience (~80%), with backend familiarity (~20%)
- Proficiency with build tools like Webpack, Rollup, Esbuild, including code obfuscation and minification
- Experience with modern testing frameworks such as 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
- Experience with WebAssembly, browser extensions, or remote debugging
- Familiarity with AWS services such as Lambda, CloudFront, and DynamoDB
- Browser automation or scraping experience
We have noticed a rise in recruiting impersonations across the industry, where scammers attempt to access candidates' personal and financial information through fake interviews and offers. All Fingerprint recruiting email communications will always come from the @fingerprint.com domain. Any outreach claiming to be from Fingerprint via other sources should be ignored.
Offers vary depending on, but not limited to, relevant experience, education, certifications/licenses, skills, training, and market conditions.
Due to regulatory and security reasons, there’s a small number of countries where we cannot have Fingerprint teammates based. Additionally, because Fingerprint is an all-remote company and people can join our workforce from almost any country, we do not sponsor visas. Fingerprint teammates need to be authorized to work from their home location.
We are dedicated to creating an inclusive work environment for everyone. We embrace and celebrate the unique experiences, perspectives and cultural backgrounds that each employee brings to our workplace. Fingerprint strives to foster an environment where our employees feel respected, valued and empowered, and our team members are at the forefront in helping us promote and sustain an inclusive workplace. We highly encourage people from underrepresented groups in tech to apply.
🎯 Who is this job for?
This role is perfect for a Senior JavaScript Engineer with deep expertise in browser-side development, TypeScript, and performance-critical SDKs. Ideal candidates have experience with browser APIs, anti-debugging techniques, obfuscation, and security-focused engineering, and are comfortable working independently in high-stakes environments. It suits developers who enjoy building tamper-resistant, high-performance libraries and contributing to widely-used open-source tools.
💬 Potential Interview Questions
-
Explain your experience building JavaScript/TypeScript libraries or SDKs for browser environments.
I have developed production-grade SDKs optimized for performance and compatibility, focusing on minimal footprint, stealth features, and cross-browser support. -
How do you optimize JavaScript code for size and execution speed in adversarial browser environments?
I use advanced bundlers like Webpack and Rollup with code splitting, tree shaking, minification, and obfuscation, while profiling to reduce runtime overhead and prevent detection. -
Describe your understanding of browser APIs and common anti-debugging techniques.
I deeply understand DOM manipulation, event loops, timing attacks, and techniques like function inlining prevention, debugger detection, and code virtualization to resist tampering. -
What approaches do you take to ensure security and privacy best practices in frontend SDK development?
I implement strict input validation, avoid storing sensitive data in accessible scopes, use secure communication protocols, and follow principles of adversarial engineering. -
How do you stay updated on browser changes and fingerprinting countermeasures?
I monitor browser release notes, security advisories, developer forums, and actively participate in relevant open-source communities and research publications. -
What testing frameworks and CI practices do you use for browser SDKs?
I use Jest and Jasmine for unit and integration tests, alongside automated cross-browser testing in CI pipelines to ensure functionality across platforms. -
Describe your collaboration experience with backend, security, and data science teams.
I coordinate closely to align frontend signal capture with backend detection logic, ensuring seamless data flow and robust fraud detection systems. -
Have you contributed to open-source JavaScript or TypeScript projects?
Yes, I have contributed bug fixes and feature enhancements to popular libraries, improving performance and expanding compatibility. -
What experience do you have with build tools like Esbuild, Webpack, or Rollup?
I configure these tools for optimized builds, integrating plugins for code obfuscation, minification, and managing multi-entry points in complex projects. -
Are you familiar with AWS services relevant to CDN and serverless architectures?
Yes, I have worked with AWS Lambda, CloudFront, and DynamoDB to deploy scalable, performant SDK backends and API integrations supporting frontend clients.
📋 Job Summary
Fingerprint is seeking a JavaScript Engineer to develop and maintain their high-performance, tamper-resistant browser-side SDK used globally for fraud detection. This remote role focuses on crafting stealthy, resilient TypeScript/JavaScript code optimized for speed and minimal footprint, while collaborating across security, backend, and data science teams. Ideal candidates have deep expertise in JavaScript/TypeScript, browser APIs, security best practices, and experience building production-grade SDKs or libraries. Join a company backed by top investors, contributing to a popular open-source project with over 24K GitHub stars and billions of monthly uses, while working in a fast-paced, autonomy-driven environment.