Senior Software Engineer, Browser Extensions

Senior Software Engineer – Browser Extensions (Manifest V3, TypeScript)

Location: Pune, India (Hybrid – 2 days onsite)

Level: L5

Experience: 8–15 Years

Build the Browser Security Platform Protecting Millions of Students

At Securly, we're redefining how web filtering works on ChromeOS.

Instead of sending every request to the cloud, we're building an intelligent, on-device filtering engine that makes real-time security decisions directly inside the browser. The result is dramatically faster filtering, greater reliability, stronger resistance to bypass attempts, and a better experience for more than 20 million students worldwide.

We're looking for an experienced Browser Extension Engineer who has deep expertise in Manifest V3, TypeScript, and modern browser security architecture. You'll own one of the most technically challenging parts of our platform—designing and building the local policy engine that powers filtering decisions directly on student Chromebooks.

This isn't typical frontend engineering.

You'll work at the intersection of browser internals, security engineering, distributed systems, caching, and performance optimization while helping shape the future of browser-based security.

Why This Role Is Different

You'll own the architecture behind an extension deployed at massive scale.

Your work will include:

• Building an onboard filtering engine that performs policy decisions locally instead of relying on cloud round trips
• Designing high-performance local policy caches with delta synchronization and offline resilience
• Developing real-time filtering logic inside Manifest V3 service workers
• Engineering defenses against sophisticated bypass techniques
• Optimizing performance for millions of low-resource Chromebook devices
• Helping define Securly's long-term browser platform strategy as Google evolves ChromeOS Content Filtering APIs

You'll have significant technical ownership and influence over both today's architecture and tomorrow's platform direction.

What You'll Build

As the technical owner of Securly's Browser Extension platform, you will:

• Design and build our onboard filtering engine using TypeScript and Manifest V3
• Architect local policy caching, synchronization, expiration, and recovery mechanisms
• Implement real-time filtering decisions for domains, URLs, iframes, and embedded content
• Design secure browser architectures that prevent policy bypass and abuse
• Build high-performance service workers with minimal memory and CPU impact
• Optimize extension startup time, runtime performance, and storage efficiency
• Evaluate evolving ChromeOS platform capabilities and recommend future architectural direction
• Mentor engineers through architecture reviews, design discussions, and code reviews

What We're Looking For

Required

Expert TypeScript & JavaScript

• 5+ years building production software
• Deep understanding of asynchronous programming, event-driven architecture, Promises, memory management, and modern JavaScript

Manifest V3 Browser Extensions

• Extensive production experience building Chrome Extensions using Manifest V3
• Service Workers
• Content Scripts
• Messaging
• chrome.storage
• declarativeNetRequest
• Extension lifecycle
• Extension permissions

Browser Security

Strong understanding of:

• Same-Origin Policy
• Content Security Policy (CSP)
• CORS
• iframe security
• Sandboxing
• Browser process isolation
• Content Script vs Page Context
• Extension attack surfaces

Performance Engineering

Experience optimizing applications running on constrained hardware.

You understand:

• Service Worker lifecycle
• Memory pressure
• Startup latency
• Storage limits
• Efficient caching strategies

Architecture

You're comfortable designing systems rather than simply implementing tickets.

You write design documents, evaluate tradeoffs, and help teams make sound technical decisions.

Preferred Experience

• Firefox, Edge, Brave, and Chromium extension development
• Extension migration from Manifest V2 to Manifest V3
• Local-first or offline-first application architecture
• Delta synchronization protocols
• IndexedDB
• Chrome DevTools performance profiling
• URL categorization or web filtering technologies
• Enterprise browser management
• Playwright or Puppeteer extension testing

You'll Thrive Here If...

You enjoy solving problems most developers never encounter.

You understand browsers beyond the DOM—you know how extensions execute, how service workers behave, and where security boundaries exist.

You think about attack vectors before writing code.

You care deeply about performance.

You enjoy owning architecture rather than simply implementing features.

Most importantly, you're excited about building software that protects millions of students every day.

About Securly

Securly protects more than 20 million students across 20,000+ schools worldwide.

Our platform processes over 1.1 billion web requests and 54 TB of data every day, making us one of the largest cloud-native student safety and web filtering platforms in education.

For more than a decade, we've helped schools create safer digital learning environments through innovative technology that combines security, performance, and student wellness.

Benefits

• Comprehensive Health Insurance (Employee + Family)
• Parents Medical Coverage
• Life & Accident Insurance
• Learning & Development Reimbursement
• Paid Time Off
• Public Holidays
• EPF & Gratuity
• Hybrid Work Environment
• Collaborative Engineering Culture

Equal Opportunity Employer

Securly is proud to be an Equal Opportunity Employer. We celebrate diversity and are committed to creating an inclusive environment for all employees.