Staff Browser Extension Engineer at Zscaler

Zscaler (NASDAQ: ZS) accelerates digital transformation so customers can be more agile, efficient, resilient, and secure. The Zscaler Zero Trust Exchange platform protects thousands of customers from cyberattacks and data loss by securely connecting users, devices, and applications in any location. Distributed across 200+ public data centers globally and thousands of private sites at the edge, the SASE-based Zero Trust Exchange is the world’s largest in-line cloud security platform.

We believe the future of work is Human + AI and are building an AI-native enterprise where human potential is amplified by machine intelligence to solve the world’s hardest security challenges. Driven by deep customer obsession, we are committed to the mission, outcome, and to each other. We bring these commitments to life through three core behaviors: ownership and collaboration, trust through outcomes and impact, and a challenge culture with ongoing feedback. Ready to make an impact at the company pioneering security transformation in the AI era? Join us at Zscaler.

Role

We are looking for a Browser Extension Engineer to join our team. This is a Hybrid (Bangalore) role, reporting to the Director, Threat Researcher in the Engineering department. Zero Trust Browser is our Browser Detection and Response (BDR) extension that lives inside Chrome, Firefox, and Safari to protect users where they actually work by detecting threats, enforcing enterprise policy, and analyzing content in real time without slowing anyone down.

This is not a typical frontend role; most of the work happens beneath the UI layer in code that runs on every page a user visits across browsers we do not control and websites we have never seen. The core engineering challenges center on the browser itself: how pages load, how extension contexts communicate, how to stay fast and invisible, and how to build controls that hold up against active evasion. You will join a small, senior team as a hands-on individual contributor, owning features end to end and shaping how a large, modular codebase grows.

What you’ll do (Role Expectations)

• Design and ship extension features end to end, from the detection or enforcement logic in the browser to the user-facing experience around it
• Write code that runs on every page load for millions of users, where speed, memory, and "don't break the website" are product requirements
• Think like an attacker about your own work, and build controls that are hard to bypass
• Handle the differences between Chrome, Firefox, and Safari behind clean abstractions the rest of the team can rely on
• Diagnose problems you can't reproduce locally, using telemetry and good instrumentation

Who You Are (Success Profile)

• You act like an owner with a passion for the mission and a strong bias for action, operating with integrity and navigating seamlessly between high-level strategy and hands-on execution.
• You are a high-trust collaborator who embraces a culture of candid feedback delivered with clarity and respect to build team success and mutual trust.
• You are customer-obsessed, anchoring your decisions in solving real-world problems and championing user needs from start to finish.
• You are driven by innovation and energized by complex technical challenges, constantly seeking better, more secure, and scalable solutions.
• You lead with integrity by holding yourself and others to high standards of accountability and building trust through consistent, transparent action.

What We’re Looking for (Minimum Qualifications)

• Foundational understanding of AI/ML technologies and experience leveraging, securing, or positioning AI-driven solutions to optimize outcomes within your functional domain
• 5+ years of software engineering experience, with deep, hands-on TypeScript or JavaScript
• Browser-extension experience on Chrome, Firefox, or Safari: extension APIs, manifest versions, permission models, and how content scripts, background workers, and extension pages fit together
• Strong knowledge of the web platform itself, not just a framework on top of it: how pages load and execute, the DOM and its event model, iframes and cross-origin boundaries, web workers, browser storage, and security features like CSP
• A genuine mental model of JavaScript: async behavior, closures, modules, and a type system you use to prevent bugs rather than annotate them
• Comfortable building UI with any reactive library (React, Vue, Svelte, or similar) based on a deep understanding of state and rendering

What Will Make You Stand Out (Preferred Qualifications)

• Proven ability to leverage AI technologies and workflows to drive measurable operational efficiency
• Published browser extensions and third-party code executing on unowned pages (e.g., analytics agents, embedded SDKs/widgets, payment or login iframes, bookmarklets, and userscripts)
• Proven experience architecting IPC-driven multi-process desktop applications, engineering AppSec solutions, building browser automation/anti-bot systems (Puppeteer, Playwright, CDP), or managing low-level DOM and custom build pipelines (esbuild, Rollup, Wasm)

At Zscaler, we are committed to building a team that reflects the communities we serve and the customers we work with. We foster an inclusive environment that values all backgrounds and perspectives, emphasizing collaboration and belonging. Join us in our mission to make doing business seamless and secure.

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