Grab Browser Extension

Sends browser downloads and links to the Grab download manager (MV3, Chromium and Firefox).

Grab 5.7.0 or newer required for automatic interception (it uses Grab's local HTTP endpoint); Alt+G and the context menu work with 4.7.1+. Install Grab from FlatPark via the badge above.

Install

From a release zip

1. Download grab-extension-<version>.zip (Chromium/Brave) or grab-extension-firefox-<version>.zip (Firefox) from the releases page.
2. Extract it, then load it in your browser:
   • Chromium/Brave: open chrome://extensions, enable Developer mode, Load unpacked → select the extracted folder.
   • Firefox: open about:debugging#/runtime/this-firefox, Load Temporary Add-on → select the manifest.json inside the extracted folder.

No native host setup needed. Automatic interception posts each URL to Grab's local endpoint (http://127.0.0.1:9412/add); Alt+G and the context menu hand grab:// URLs to the browser, which routes them to Grab via the OS scheme handler.

Developer mode (from source)

1. Clone the repo and open chrome://extensions, enable Developer mode.
2. Load unpacked → select the repo folder.

Grab must be installed with its desktop entry (it registers as the x-scheme-handler/grab handler, used by Alt+G and the context menu).

What it does

• Automatic interception (off by default, enable in settings): downloads started in the browser are cancelled and sent to Grab over its local HTTP endpoint. If Grab isn't running or doesn't accept the request, the download stays in the browser. Grab asks for confirmation unless auto-add is enabled in its preferences. If a tiny download finishes before the cancel lands, the duplicate is removed from the browser.
• Toolbar button: opens a popup with the extension settings (adapts to your system's light/dark theme).
• Alt+G: sends the current tab to Grab (video pages open the New Download card, other links download normally).
• Right-click → Download with Grab: on links, images, video, audio, and pages.
• Video detection (on by default): videos you've started playing in the tab — including streams behind blob: players — appear under right-click → Videos detected by Grab, with a count badge on the toolbar button. Picking one opens it in Grab, which probes it like any other link. Skipped on video platforms yt-dlp handles itself (YouTube, TikTok, Instagram, Facebook, X, Twitch, Vimeo, …) — a detected media URL can't work there, so sending the page goes through yt-dlp the usual way.
• Options page: same settings as the popup, in a full page (via the popup's "Full options page" link or right-click → Options).

Magnet links are passed to the OS untouched — Grab already handles magnet:. blob: and data: URLs can't be handed off and always stay in the browser.

Limitations

• Downloads that need the browser's session (logged-in direct links) forward the site's cookies to Grab — but only after you pair the extension (see below). Unpaired, handoffs are URL-only.
• POST-form downloads hand Grab the action URL, which may not resolve to the file.
• Automatic interception requires Grab to be running. URLs longer than 2048 characters are refused by Grab and stay in the browser.
• The browser's download is cancelled once Grab confirms it took over; if you decline in Grab's confirmation dialog, the download is not restored.

Pairing with Grab

Grab listens on 127.0.0.1:9412. Any local program could pretend to be Grab, so the extension only sends cookies to a Grab that proves it knows a shared secret:

1. In Grab, open Preferences → Browser extension and copy the pairing code.
2. In the extension's Options page, paste it into the Pairing section and click Pair. Your browser will ask for the cookies permission — it is optional and only requested here, on your click.
3. The extension verifies Grab (/hello challenge) before every cookie handoff. If verification fails, the handoff is URL-only.

If you click Regenerate in Grab's Preferences, pair again — the old code stops working immediately.

Permissions

downloads (cancel intercepted downloads), contextMenus, storage (settings), alarms (size-wait deadlines that survive worker restarts), activeTab (read the current tab's URL for Alt+G), webRequest (spot video stream manifests), host access to http/https pages (video detection; also lets the background script POST to Grab's loopback endpoint).