You don't need a Kindle hardware device to read these files. You can use:
A free, powerful ebook management tool. To convert, add your file to the Calibre library, click "Convert books," and set the output format to MOBI. Download File (MOBI)
Tools like the "MOBI Reader" extension for Chrome allow you to read ebooks directly in your browser. MOBI Support for eBooks Frequently Asked Questions You don't need a Kindle hardware device to read these files