AddThis
629,840 websites

AddThis is free to use

http://www.addthis.com

AddThis, the new brand name for Clearspring Technologies, is the leader in socially connecting publishers, services and advertisers to audiences on the open web. Reaching more than 1.3 billion unique users monthly, AddThis’ social tools and...

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Facebook Page Administration
500,743 websites

Facebook Page Administration is free to use

http://developers.facebook.com/docs/opengraph

Identifies administrators for a page which will be able publish data to your wall if you like any content within this page.

Market Share by Top Websites

1 AddThis is leading in Top 1M Sites and The Entire Web.

2 Facebook Page Administration is leading in Top 10K Sites and Top 100K Sites.

Websites Categories

1 AddThis has better usage coverage in more websites categories. Including Science & Education, Arts & Entertainment, Adult, Health and 15 other categories.

2 Facebook Page Administration is leading in Computers Electronics & Technology, Food & Drink, News & Media, Games and one other category.

Geography

1 AddThis is leading in most countries, including United States, United Kingdom, Italy, Canada and 127 other countries.

2 Facebook Page Administration is leading in Japan, France, Brazil, Germany and 31 other countries.