Pinboard can automatically import your links and tweets from a number of outside services. The archive feature saves a local copy of everything you bookmark in case the original page goes offline, and offers full-text search. Currently 11 USD annual fee, with an optional 25 USD fee for archiving.
Plurk is a free social networking and micro-blogging service that allows users to send updates (otherwise known as plurks) through short messages or links, which can be up to 210 text characters in length (previously 140).
The site was bought by Avos Systems on April 27, 2011 though was operated by Yahoo! until July 2011. On June 1, 2017, Delicious was acquired by Pinboard, and the service will be discontinued. As of March 2018, the website is read-only.
Syncs bookmarks (folders & sub-folders) and profiles across different browsers and platforms. Includes sharing option and possibility to access bookmarks via web-based-interface. On May 1, 2018, Xmarks was discontinued after being acquired by LastPass.