How offline mode works
First visit
CrabPDF downloads and caches everything it needs — the editor, PDF tools, and all dependencies.
After that
The app loads from your device's cache. No internet needed. Turn off Wi-Fi and it still works.
Your files stay local
PDFs never leave your machine. Everything runs in the browser — offline or not.
Automatic updates
When you're online and a new version is available, it updates silently in the background.
Install on Chrome or Edge
Chrome and Edge let you install CrabPDF as a standalone app that opens without a browser tab.
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Open CrabPDF in Chrome or Edge
Visit crabpdf.com and wait a few seconds for the app to fully load.
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Look for the install icon in the address bar
In Chrome it looks like a monitor with a down arrow (⊕). In Edge it's a similar icon on the right side of the address bar.
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Click "Install"
Confirm the dialog. CrabPDF will open as its own window and appear in your app launcher or taskbar.
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Use it offline
Open CrabPDF from your launcher at any time — no browser, no internet required.
Official guide: Install and manage apps in Chrome · PWA in Microsoft Edge
Android and iOS
CrabPDF is not supported on mobile. The editor requires a large screen and mouse/trackpad input — it will not work correctly on a phone or tablet. Use it on a desktop or laptop.
Firefox
Firefox on desktop does not currently support installing PWAs as standalone apps, but CrabPDF still works offline in a Firefox tab — the service worker caches everything after your first visit. On Android, Firefox supports "Add to Home screen" via the browser menu.
Related
No-upload PDF editor · All features · Edit PDF text · OCR scanned PDFs