| .a4p |
A4Desk Pro Project File |
| .aplg |
Audials Plug-in |
| .aplp |
Audials Plug-in Package |
| .adv |
Audio Driver File |
| .accft |
Microsoft Access Data Type Template |
| .aec |
Cinema 4D After Effects Composition |
| .acorn |
Acorn Image |
| .avhd |
Hyper-V SnapShot File |
| .avv |
Avid Volume Bin File |
| .ane |
Adobe AIR Native Extension |
| .appdownload |
Mac App Store Partially Downloaded App |
| .aes |
AES Crypt Encrypted File |
| .appx |
Windows 8 App Package |
| .appxupload |
Windows 8 App Upload Package |
| .accountpicture-ms |
Windows 8 Account Picture File |
| .artb |
Artboard Document |
| .aaui |
Acrobat User Interface File |
| .aepkey |
Advanced Encryption Package Key File |
| .amm |
All My Movies Database File |
| .amb |
All My Books Database File |
| .acg |
Audio Comparer Group File |
| .a2i |
Adlib Tracker II Instrument File |
| .asv |
Finale Auto-save File |
| .asef |
GrabCAD 3D CAD model file |