Facebook Messenger is not available for Kindle Fire but there are a few alternatives with similar functionality. The best Kindle Fire alternative is ICQ, which is free. If that doesn't suit you, our users have ranked more than 100 alternatives to Facebook Messenger and four of them are available for Kindle Fire so hopefully you can find a suitable replacement. Other interesting Kindle Fire alternatives to Facebook Messenger are IM+ (Freemium), Facebook Messenger Kids (Free) and Mobilevoip (Free).
ICQ is one of the oldest instant messengers. First developed by the Israeli company Mirabilis, sold to AOL, sold again and currenly owned by the Russian "mail.ru" group (known for one of the largest social networks).
Messenger Kids is a free video calling and messaging app designed for kids to connect with close friends and family from their tablet or smartphone. Kids can only connect with parent-approved contacts, which creates a more controlled environment.
MobileVOIP is a free cheap calls app which lets you make (free) national or international mobile voip calls directly from your iPhone. You can save on your Mobile Phone costs by simply installing the MobileVOIP app and start making cheap calls.