| apj | Autodesk AutoCAD Architecture Project |
| apk | Active Tutor Project |
| app | CA Visual Objects Project |
| approj | ActivePresenter Project |
| apr | Apadana Project |
| apr | Vector NTI Alignment Project |
| aprj | ApacheConf Project |
| aproj | Leapfrog Geo Project |
| aprx | Vector NTI Alignment Project |
| apt | appTranslator Project |
| apt | AutoPlay Media Studio Template |
| apz | Autoplay Media Studio Exported Project |
| arcproj | ARRIRAW Converter Project |
| argo | ArgoUML Project |
| arh | ArheoStratigraf Project |
| arh | Siemens ProTool Compressed Project |
| arp | Arlequin Project |
| arproj | Spark AR Studio Project |
| art42 | Bernina Explorations v1.x Project |
| art50 | Bernina Embroidery Software v5.0 Design |
| art60 | Bernina Embroidery Software v6.0 Design |
| artproj | Artifacts for Visual Studio Project |
| artx | Artisteer Project |
| as2proj | FlashDevelop Project |
| as3proj | FlashDevelop Project |
| ashprj | Ashampoo Burning Studio Project |
| asmproj | Atmel Studio Assembler Project |
| asprj | Altova XMLSpy Scripting Project |
| asproj | Visual Studio Analysis Services Project |
| assembly | DNASTAR SeqMan NGen Assembly Project |
