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Auto Tab Discard is an add-on for the Firefox and Chrome web browsers that frees up memory that the web browsers uses by discarding inactive tabs. Discarding in this context means that the tabs are unloaded but kept open in the browser.

Web browser users who keep multiple tabs open in the browser of choice may notice that memory use increases with each tab that gets opened.

Both Google and Mozilla have developed systems to unload tabs in low memory situations, but these solutions are not as efficient as those provided be extensions.

We reviewed numerous in the past including Sleep Mode for Firefox or Lazy Load Tabs for Chrome. Most Firefox extensions that used to work in the browser were not updated when Firefox 57 was released.

Auto Tab Discard

Auto Tab Discard runs automatically in the background. The default setting unloads tabs after 600 seconds of inactivity if the number of inactive tabs exceeds six tabs.

Tabs are not discarded when they meet certain criteria, e.g. when media is playing or form changes have not been submitted. Additional discarding conditions are listed in the options. The following conditions need to be enabled manually:

* When a tab is pinned.
* When there is no Internet connection and tabs have not been cached.
* When it is allowed to display desktop notifications.
* When computer is not in idle state.

One of the strengths of the extension is that it provides lots of customization options. You can change the unloading interval or number of inactive tabs required as well as criteria that prevent or allow tabs and sites to be discarded by the extension.

Sites that match criteria are not discarded but there is also an option to add sites to the whitelist to prevent that they are unloaded by the extension. Discarded tabs are retained even across sessions; they remain discarded until activated by the user.

Information such as the scroll position or text inside text fields is retained by the extension and loaded when a site becomes activate again. JavaScript and other code is not run anymore when tabs are discarded.
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