AZW4 file format is used by e-book reader Amazon Kindle. AZW4 files typically store digital documents in a form of a textbook. AZW4 format is base on MOBI digital publishing standard.

AZW4 files are DRM-restricted to prevent the files from unauthorized use that violates the license agreement. AZW4 file data is encrypted. and in order to view the content user must possess appropriate license key.