View JSON formatted bookmarks in your browser. Just drag and drop the bookmarks file onto your browser window (javascript has to be enabled).
View demo.
Open the bookmarks manager (Ctrl+Shift+O), select Import and Backup > Backup ... and save the JSON file to the selected location.
As far as I know, all Chromium based browsers store their JSON formatted bookmarks in a file called Bookmarks located in the user's profile directory (tested with the portable installations of Chrome, Opera and Vivaldi). I couldn't find any option to export the bookmarks from the browser, so you'll have to manually look for the file.