What are some alternatives?
When comparing Word Online and calibre, you can also consider the following products
Apache OpenOffice Writer - Open-source word processor of the Apache OpenOffice suite.
FBReader - FBReader is an e-book reader for various platforms. Features:
LibreOffice - Writer - Open-source cross-platform word processor.
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
Google Drive - Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
Cool Reader - Fast and small cross-platform eBook reader for desktops and handheld devices