Flowstop: Tab Blocker & Offline Mode

True offline mode for specific browser tabs — uses Chrome DevTools Protocol for airtight per-tab network isolation

Absolute control of your browser's internet connection. Flowstop is a precision network isolation tool that lets you instantly cut the internet to any specific tab—without affecting the rest of your browser. When Flowstop is active, the tab behaves exactly as if you unplugged your Wi-Fi: navigator.onLine flips to false, Service Workers enter offline mode, and the page shows its native offline UI. 🔒 TRUE OFFLINE SIMULATION Unlike URL blockers that just intercept requests, Flowstop uses Chrome's native DevTools Protocol to emulate a real network disconnect at the tab level. This is the exact same mechanism Chrome DevTools uses when you tick the "Offline" checkbox—but scoped to individual tabs and accessible with a single click. • navigator.onLine correctly reports false • Real "offline" events fire on window • Service Workers enter their genuine offline code paths • PWAs trigger their real offline fallback UI • The actual ERR_INTERNET_DISCONNECTED dinosaur page appears ⚡ INSTANT & LIGHTWEIGHT • One-click toggle from the popup or ⌘+Shift+F keyboard shortcut • Visual "OFF" badge on isolated tabs so you always know what's blocked • Clean management UI showing all offline tabs at a glance • Restore any tab's connection with a single click 🎯 PERFECT FOR • Developers — Test how your web app, PWA, or Service Worker handles real offline conditions without disconnecting your entire machine • Privacy & Security — Stop a loaded page from phoning home, sending analytics, or tracking your behavior while you read it • Focus & Productivity — Park distracting tabs (social media, news feeds) without closing them. Kill live notifications, auto-refreshes, and streaming connections • Journalists & Researchers — Review sensitive documents without the page silently transmitting data back to its servers • Bandwidth Control — On metered data? Isolate heavy tabs to stop background downloads and video preloading 🛡️ PRIVACY-FIRST DESIGN Flowstop is 100% offline and open-source. It makes zero external network requests. No analytics. No telemetry. No data collection of any kind. Your browsing data never leaves your machine. Note: Because Flowstop uses Chrome's native debugging protocol to ensure airtight network isolation, Chrome displays a yellow banner ("Flowstop started debugging this browser") on isolated tabs. This is a built-in Chrome security feature—it confirms that the tab's network is being controlled and ensures full transparency.