Google Chrome
Up to 720p on Windows, Mac, and Linux
Up to 1080p on Chrome OS
Internet Explorer up to 1080p
Microsoft Edge up to 4K*
Mozilla Firefox up to 720p
Opera up to 720p
Safari up to 1080p on Mac OS X 10.10.3 or later
I know, that's why I tried IE, edge and also the native Windows app. The quality is still crappy. In fact I wanted to watch the movie Pacific Rim, and the quality was so bad that it was unwatchable. I torrented a 1080p copy and watched that instead.
As I said, the weird part is that their is no improvement in quality even if you pre-download the content.
Other browsers are at a lesser resolution, I believe it was 720p but that could be wrong.
Edit: yup, 720p on everything except IT.
https://help.netflix.com/en/node/23742
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