.BLT File Extension
What is a BLT file?
Stores a list of user's friends for AOL Instant Messenger (AIM), a popular instant messaging program; contains usernames and other information about friends that appear in the program's "buddy list;" the buddy list provides an easy way to contact friends and see what friends are online.
BLT files were used by AIM 5.9 and earlier.
NOTE: AOL discontinued Instant Messenger on December 15th, 2017.