Securly - Senior Software Engineer - Browser Extensions

Senior Software Engineer - Browser Extensions (MV3 Javascript)Location : Pune, India Remote-Friendly / Hybrid | L5

Experience : 8 -15 Years

**Build the filtering engine protecting 20 million students inside the browser.

Securly processes 1.1 billion web requests every day across 20,000+ schools worldwide. Right now, every filtering decision requires a cloud round-trip. We're eliminating 80% of those round-trips by moving the filtering decision engine directly into the Chrome extension itself - running on-device, inside a Manifest V3 service worker, on student Chromebooks.

This is the role that builds that engine.

This is not a frontend role. Not full-stack. Not AI. This is deep Chrome Extension platform engineering - service worker lifecycle, local policy caching with delta sync, real-time URL filtering, and bypass prevention against students actively trying to defeat your controls. If that's where you live as an engineer, read on.

Location and Work Model :

This role is primarily remote with occasional in-person collaboration at our Pune office. You should be based in India and able to travel to Pune when needed. We are flexible for the right candidate.

What You'll Own :

• Architecture and implementation of the onboard filtering engine - local policy cache, delta sync protocol, filtering decision engine, and bypass prevention layer.

• Local policy cache with TTL management, cache invalidation, and graceful cloud fallback - designed to work when connectivity is unreliable.

• Real-time filtering decision engine inside the MV3 service worker - domain matching, URL categorization, iframe detection, allow/block decisions.

• Bypass prevention hardened against adversarial students - same-origin policy, CSP, CORS, iframe sandboxing, content script/page context boundaries, timing-based attack vectors.

• Performance optimization for consumer-grade Chromebook hardware - negligible latency, tight memory budgets, efficient storage within chrome.storage.local and IndexedDB limits.

• Architecture memos evaluating Google's Filter and Monitor platform shift and its implications for Securly's extension-vs-network-layer strategy.

What You Must Bring :

• TypeScript and JavaScript : expert level. async/await, Promises, event-driven architecture, memory management in long-running service workers. 5+ years at this depth.

• Chrome Extension MV3 : production experience. Service workers, content scripts, chrome.storage, declarativeNetRequest, webRequest APIs. Not general JS experience applied to extensions - extension platform engineering as your primary domain.

• Browser security model : same-origin policy, CSP, CORS, iframe sandboxing, content script vs page context boundary. You know where the security boundaries are and what happens when they break.

• Security-first architecture : you enumerate attack surfaces before writing the first line of code. At L5, you define the threat model, you don't just implement against one handed to you.

• Local caching and offline-first architecture : delta sync, TTL management, cache invalidation, chrome.storage.local limits, IndexedDB for larger policy stores.

• Technical communication - written ADRs, threat model documents, and platform evaluation memos that inform cross-team strategy.

Strongly Preferred :

• MV2 to MV3 migration experience.

• Web filtering, URL categorization, or content classification.

• Chrome DevTools performance profiling on low-end hardware.

• Cross-browser extension development (Firefox, Edge, Arc).

• Google Filter and Monitor / ChromeOS Content Filtering API awareness.

Nice to Have :

• Playwright or Puppeteer with extension loading for test automation.

• ChromeOS / Google Admin Console enterprise extension management.

• K-12 EdTech domain familiarity.

• Kotlin.

What L5 Means at Securly :

L5 is a Staff Engineer. You own your initiative from architecture to production with minimal oversight. You mentor L3/L4 engineers, partner directly with our Distinguished Engineer on architectural decisions, write artifacts that leadership and product can act on, and own the full incident lifecycle for your system.

About Securly :

Securly has been protecting students online since 2013 - the first cloud-based web filter built for K-12. Today we protect 20 million students across 20,000+ schools, processing 1.1 billion requests and 54 TB of data every day. We are consistently recognized as a Top Place to Work, a Top 40 Most Used EdTech platform, and a GSV 150 company.

Benefits :

• Comprehensive Health Insurance (employee, spouse, children, and parents)

• Accidental and Term Life Insurance

• Learning and Development Reimbursement

• Paid Time Off - 10+ Public Holidays

• EPF and Gratuity

• Parental Leave

• Hybrid Work Environment.

Securly is an Equal Opportunity Employer. We welcome applicants from all backgrounds, identities, and experiences.