Simple and effective.

I'm not sure about this add-on, It sounds usefull.... but it should add feature such as comparation "save data & without save data" in Mb and total saving data in days/weeks/months.

But the most important is all features should not make Firefox consumes big RAM.

It should add 'Exclude Websites' function to exclude websites that become broken/dysfunctional because of this add-on, like one of my shopping sites.

Thanks, Daniel! This extension works perfectly. :)

I'm kind of disappointed that it's even necessary to have an extension for this because there's no such setting in Firefox out of the box.

Please add a UI to turn the addon on or off.

Bless you, I'm on a satellite internet and burn through my allotted data about a week early each month, this will help!

For now under test. But I'm really enjoying the speed.

2017-12-05　最新のFirefoxで試しましたが、URL先頭に Save-Data:をつけてもページ遷移しませんでした。

Stable and works fine than data saver proxy...

Doesn't actually reduce your data usage per say, but does as advertised: it informs websites that you're data conscious and want them to make an effort to reduce their impact on your data usage.