Applications to convert your ebook from DOCX to MOBI:
2EPUB is a free online tool that allows you to convert various types of documents and e-books to ePub format, the standard file format for e-books that is supported by almost every e-book reading device including iPad, Sony Reader, BeBook, IREX Reader, iPhone, Nook, etc. Read more »
This online application can convert to and from different formats. The application lets you convert one or multiple files and select the output format of every file. If you don't have a Convertio account, it allows a maximum file size of 105 MB. If you sign up, the file size limit is increased to 1 GB. Read more »
Calibre is a free and open source e-book library management application. It can convert from a huge number of formats to a huge number of formats. The conversion engine has lots of powerful features. It can rescale all font sizes, detect/create book structure, insert the book metadata, etc. Read more »
Mac OS X, Windows 7, Windows Vista, Linux, Windows XP.
If you want to convert files you have hosted on Dropbox, Google Drive or an URL, this application is what you need. The free version allows a maximum upload file size of 100 MB, 10 minutes of conversion time and 2 concurrent conversions. Read more »