The AZW file type was developed by Amazon for use with their range of Kindle eBook readers. Kindle File Format is a proprietary e-book file format created by Amazon. AZW files are used on Amazon's Kindle eBook reader devices, so you'll likely see this type of file when you're downloading eBooks from the. Amazon developed the AZW format as the project output files integrated with specifications and standards used by the Amazon Kindle reader device. The Portable Document Format (PDF) is a file format used to present documents in a manner independent of application software, hardware, and operating.