As of July 2, 2018, Co:Writer Universal for Desktop Mac and PC version 1.0.0.4 (released March 12, 2015) has entered End-of-Life status.  No updates will be made to this version. Support for this version has also been discontinued.  

For the most current version of Co:Writer Universal for OS X, Windows, iOS, and Chrome OS, please see...

 https://chrome.google.com/webstore/detail/cowriter-universal-extens/ifajfiofeifbbhbionejdliodenmecna
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​https://chrome.google.com/webstore/detail/cowriter-universal-chrome/lahlmdogjpblkonckkgbljegkiijjbag

https://microsoftedge.microsoft.com/addons/detail/cowriter/ibbhadmnjccbljgfehndobbpjghoccio?hl=en-US
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​https://itunes.apple.com/us/app/co-writer-universal/id915105799. 

"End of Life" refers to the process of discontinuing this specific version of the product. While the product still remains available through the most current offering (as linked to above), this particular version of Co:Writer will cease to be supported and will no longer be made available.  
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