| adicht | ADInstruments LabChart Chart Data |
| adidat | ADInstruments LabChart Simple Data |
| adif | Amateur Data Interchange Format File |
| adiumlog | Adium Chat Log |
| adix | XML-based ADIF File |
| adj | BenMAP Adjustment Factor File |
| adj | FARSITE Adjustment Factors Data |
| adl | openEHR Archetype Definition Language File |
| adm | Addict Dictionary |
| adm | Windows Administrative Template |
| adm | Alphacam Diecut Param Macro |
| adn | Microsoft Access Blank Project Template |
| adp | Alphacam Diecut Post Data |
| adr | z-Tree Address Data |
| ads | Agricultural Data Interchange Syntax File |
| adt | Act! Template |
| adt | Alphacam Diecut Tool Data |
| adu | Addict Custom Dictionary |
| adw | Adhawin Transliteration Scheme |
| adx | XML-based ADIF File |
| aea | AdWords Editor Archive |
| aeb | Alphacam Wire EDM VB Macro |
| aec | Cinema 4D After Effects Composition |
| aecache | Adobe After Effects Cache |
| aecap | Adobe After Effects Text Template Capsule |
| aedt | ANSYS Electronics Desktop Data |
| aedtz | ANSYS Electronics Desktop Archive |
| aeg | Netmino Data |
| aeix | ARGUS Enterprise Exported Data |
| aek | Adobe After Effects Keyframe |
| aem | STK Azimuth-Elevation Mask |
| aem | Alphacam Wire EDM Param Macro |
| aen | Inventus Antum Secured Mail Encrypted Data |
| aeo | Avid MetaSync Avid Enhancement Object |
| aep | Alphacam Wire EDM Post Data |