On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 4 on 2010-01-25 Note: Chrome treats auto as optimizeSpeed.
In Chrome Android version 18 on 2012-06-27 Note: Chrome Android treats auto as optimizeSpeed.
In Edge version 79 on 2020-01-15 Note: Edge treats auto as optimizeSpeed.
In Firefox version 1 on 2004-11-09 Note: If the font size is 20 pixels or higher, Firefox treats auto as optimizeLegibility. For smaller text, Firefox treats auto as optimizeSpeed. The 20-pixel threshold can be changed with the browser.display.auto_quality_min_font_size preference.
In Firefox for Android version 46 on 2016-04-26 Note: If the font size is 20 pixels or higher, Firefox treats auto as optimizeLegibility. For smaller text, Firefox treats auto as optimizeSpeed. The 20-pixel threshold can be changed with the browser.display.auto_quality_min_font_size preference.
Not in Internet Explorer
In Quest Browser version 5.0 on undefined Note: Quest Browser treats auto as optimizeSpeed.
In Opera version 15 on 2013-07-02 Note: Opera treats auto as optimizeSpeed.
In Opera Android version 14 on 2013-05-21 Note: Opera Android treats auto as optimizeSpeed.
In Safari version 5 on 2010-06-07 Note: Safari treats auto as optimizeSpeed. See bug 41363.
In Safari on iOS version 4.2 on 2010-11-22 Note: Safari on iOS treats auto as optimizeSpeed. See bug 41363.
In Samsung Internet version 1.0 on 2013-04-27 Note: Samsung Internet treats auto as optimizeSpeed.
In WebView Android version 4.4 on 2013-12-09 Note: WebView Android treats auto as optimizeSpeed.
In WebView on iOS version 4.2 on 2010-11-22 Note: WebView on iOS treats auto as optimizeSpeed. See bug 41363.