| .appex |
OS X Application and System Extension File |
| .assets |
Unity Asset File |
| .audionote |
AudioNote File |
| .adidat |
ADInstruments Simple Data File |
| .adicht |
LabChart Data File |
| .aegraphic |
Adobe After Effects Graphic |
| .aecap |
After Effects Text Template |
| .aur |
Aurora Timetable File |
| .acelive |
Acelive Broadcast File |
| .animeexport |
Anime Studio Export Profile Document |
| .a78 |
Atari 7800 ROM |
| .abu1 |
ASUS Backup File |
| .aiv |
AIVault Data File |
| .awc |
Emulex AWC Firmware Update File |
| .asar |
Compressed Archive File |
| .av3 |
File format used for audio and video data, stands for |
| .avr |
Audio Visual Research File |
| .avro |
Avro Data File |
| .aol |
America Online File |
| .adc |
Scanstudio 16 Color Image |
| .al |
A-Law Compressed Sound Format |
| .amu |
PictureGear Studio Photo Album File |
| .a3l |
Authorware 3 Library |
| .a4l |
Authorware 4 Library |