Hi there,
I have a question out of curiosity.
I noticed that when I export from on Glyphs-File a Web-Fonts (WOFF, WOFF2) and Desktop-Fonts (OTF) they differ in spacing.
To be more precise Web-Fonts have more tracking.
If you overall decrees tracking, the fonts mach perfect.
So fonts just run wider in browsers.
I tested this by making a screenshot of the browser and overlay this in InDesign.
It seems to be a general phenomena.
Does anyone have a explanation for this? 
thanks,
typotypo
Depends on your settings in CSS and your settings in InDesign. Both environments allow you to turn kerning on and off. InDesign also offers its own spacing & kerning algorithm, Optical Kerning. Many InD users had that turned on at one point and never noticed it after that.
@mekkablue thank you for your suggestions.
However:
We do not have added any CSS for letter-spacing ect.
We do have turned on for both kerning.
Beside of this it is the overall tracking who differs.
We have it on Metric.
I have set up a test folder with Glype file, Woff, HTML, and InDesign Test files.
If somebody are like to see the set up. 
Traking_Test.zip (975.9 KB)
I wondered whether it might be the default CSS settings at work. https://css-tricks.com/almanac/properties/t/text-rendering/
When I take a screenshot in Safari and set the size in Indesign to 25 (it says 50px in css), then it matches.
@GeorgSeifert …ah I see that is the point.
When you compare Web-Fonts in browsers with Desktop-Fonts in Applications the font-size has to be the same.
@Cormullion I tested this, CSS deafult should not vary to the Desktop Font. So there is no extra CSS neccecary, e.g. letter-spacing:0px etc.
Great, thank you all for the explaining. 
