Firefox

This page covers installing Screen Tools in Firefox and everything that works differently there. Screen Tools has the same pages and features in Firefox as in Chrome, apart from the differences below. The source for this page is docs/firefox.md.

Requirements

Screen Tools needs Firefox 140 or later, set by strict_min_version in wxt.config.ts. 140 is the first version that reads the data collection setting Firefox add-ons have to declare. Screen Tools declares that it collects no data.

Installing

Each release from v1.5.0 has a Firefox zip attached, screen-tools-vX.Y.Z-firefox.zip. Screen Tools isn't listed on addons.mozilla.org, so you load the zip as a temporary add-on:

1. Download screen-tools-vX.Y.Z-firefox.zip from the latest release. Don't unzip it.
2. Open about:debugging#/runtime/this-firefox.
3. Click Load Temporary Add-on… and pick the zip.
4. Pin the extension: click the puzzle piece (Extensions) in the Firefox toolbar, then the gear next to Screen Tools and Pin to Toolbar.

Expect: a new tab opens with the Screen Tools home page.

Firefox removes temporary add-ons when it closes, so you load the zip again each time you start Firefox. Save any recordings and screenshots you want to keep before you close it.

To update, load the new zip the same way.

Differences from Chrome

	Chrome	Firefox
What you can record	A whole screen, a window or a Chrome tab	A whole screen or a window. No tabs.
Screen picker	Chrome's picker, with screen, window and tab in one	Firefox's standard sharing prompt
System audio	System and System + mic	Not available. Use Mic or None.
Starting from the toolbar menu	Starts straight away, after a 3-second countdown	Opens the recorder and waits for you to click Start recording
Settings from the browser's add-on page	Extension options on chrome://extensions	Options in about:addons, which opens Settings in a tab
desktopCapture permission	Asked for	Not asked for. Firefox doesn't have it.

Everything else works the same: the camera overlay, autosave, Latest videos, the player, saving smaller copies, screenshots and the editor, and uploads to Google Drive, Dropbox and upload servers.

No tabs and no system audio

Firefox records the screen through its standard sharing prompt, which offers whole screens and windows but not tabs, and can't share audio. So the System and System + mic audio options don't show in Firefox. The code is in src/platform/firefox.ts and settings.ts.

Recording from the toolbar menu needs a click

Firefox only opens its sharing prompt after a click in the page. So Screen and Screen + camera in the toolbar menu open the recorder with that mode already picked, and wait for you:

1. Click Start recording.
2. Pick the screen or window to share in Firefox's prompt.

Expect: the 3-second countdown starts after you pick what to share. Camera never opens the sharing prompt, so it starts straight away as in Chrome. See recorder.tsx.

Formats and compression

MP4 is the default where Firefox can record it. Where it can't, recordings are WebM and the format select shows "MP4 (not supported)", as in Chrome. Saving a smaller copy works the same way.

Screenshots

Selected area, visible area and full page work the same way. Firefox blocks screenshots of its own pages (about: pages, addons.mozilla.org and reader view) and some others. Screen Tools shows a "Can't capture this page" notification when it does. Switch to another tab.

Permissions

Firefox asks for the same permissions as Chrome, minus desktopCapture: activeTab, scripting, notifications and storage, and the optional upload permissions when you connect a service or add an upload server. See Installation and Updating for what each one is for.