Is there any pdf viewer with dark mode?

This method is only for text only documents. Otherwise the image colors will be inverted.

You can install Evince document viewer from this link and open it.Then goto the options on the top right corner as seen in the picture.

Then select Inverted colors. This will help you to read white text on a black background. In Evince document viewer 3.30.1+ select Night Mode.

Simply inverting colors doesn't provide the best readability (being limited to very bright white text on very dark black background), although it can improve it a lot in a dark environment.

Evince, Okular and also pdfstudioviewer can do that, which will result in something like this (in both image and text pdfs):

PDF readers that can change both page and text color in both text and image (scanned text) pdf files are:

• Master PDF Editor More details in this answer, also

• Zathura - as described in this answer.

I think this is more readable:

Adobe Reader 9, which can still be used in Linux, can change both text and background color but only in text-based pdf files. More here.

See my linked answer on Foxit Reader, which can match Adobe Reader but has no dark GUI and no full-screen.

Calibre Ebook Reader (like many ebook readers) can edit colors of font and page, but it can also open text-based pdfs.

Atril from MATE DE also has Inverted Colors mode (accessible with Ctrl+I):

You can install Atril with sudo apt-get install atril.