By upgrading to a premium account you can experience better features with Diigo and access to extra content in which non-paid users do not have. Take a look into the paid services that Diigo offers.
Cached Pages
Ø Diigo can cache all of your pages so that you never have to lose past information in your bookmarks.
Ø To cache a page simply bookmark the page and there will be a box with the cache option, from there a cache version will be uploaded into your library.
Ø You can now search all of the content of your cached pages in your library.
Unlimited Features
Ø Unlimited Highlights
Ø Unlimited Bookmarks
Ø Unlimited Cache
Ø Unlimited Screenshots
Ø Unlimited Outliner
Ø Unlimited PDF
Ø Unlimited Public and Private groups
Ø Unlimited Twitter Tweet saves
PDF Annotation
Ø You can highlight and annotate your PDFs on the premium package. Just bookmark any online PDF into your library and you are ready to go!
Ø You can also access PDF’s straight from your browser to make the process even easier!
Additional Perks
Ø No Ads
Ø No Captcha
Ø Private RSS feed
Ø Priority Support
Ø Full text search