: A reliable choice that supports files up to 3MB for free users and offers an option to receive a link via email once the conversion is finished.

: Excellent for batch processing multiple files at once.

: A specialized, lightweight tool often used as a plugin for other library managers like MyHomeLib to automate the FB2 to MOBI/EPUB conversion process. Mobile Apps

: Provides advanced settings to optimize the MOBI file for specific Kindle models. Desktop Software (Best for Large Libraries)

For converting on the go, there are dedicated Android apps available on the Google Play Store that support FB2, MOBI, and EPUB formats.

If you have many books to convert, desktop software is faster and more private since it processes files locally on your computer.

: The gold standard for ebook management. It is a free, open-source program that can convert almost any ebook format (including FB2 to MOBI) while also managing your entire library and syncing with devices like Kindles.

Amazon has largely transitioned Kindles to the AZW3 or EPUB formats for modern features. If you are converting specifically for a newer Kindle, you might find that converting to EPUB or AZW3 provides a better reading experience. Ebook Converter - Apps on Google Play