| arsc | Android Package Resource |
| as | Adobe Flash ActionScript |
| AngelScript File |
| as1 | ActionScript 1.0 Source Code |
| as3 | ActionScript 3.0 Source Code |
| asa | ASP Global Script |
| asax | ASP.NET Application |
| asbx | ASP.NET BridgeHandler Data |
| asc | Adobe ActionScript Communication Script |
| ascp | Adobe Device Central Project |
| ascs | ActionScript Communication Server Script |
| Adobe Device Central Data |
| ascx | ASP.NET User Controls |
| ash | Turbo Assembler Header |
| ashx | ASP.NET HTTP Handler |
| asi | Alpha Five Variables Data |
| Assembly Include File |
| asic | ASIC Source Code |
| asm | Assembly Source Code |
| asmx | ASP.NET Web Service |
| asn | Uniface Assignment Data |
| aso | ActionScript Object |
| Turbo Assembler Compiled Object |
| asp | Active Server Page |
| asp+ | ASP.NET ASP+ File |
| asphtml | Active Server Page |
| aspr | ASProtect Related Data |
| aspx | ASP.NET Page |
| asq | AcuSQL Precompiled File |
| asr | Flash Server-side ActionScript |
| assetinfo | Amazon Lumberyard Asset Info Data |
| asv | Crestron SIMPL Program Autosave |
| MATLAB AutoSave File |
| asx | Alpha Five Database Index |
| asz | AlphaControls Skin Package |
| LoseThos Assembly Source Code |
| atc | ACUCOBOL-GT Thin Client Command File |
| atg | Coco/R Attributed Grammar File |
| atl | ATP Assembler Source Code |
| atn | Visual FoxPro Internet Search Wizard Data |
| atsln | Atmel Studio Solution |
| au3 | AutoIt v3 Script |
| aub | Intel GPU Simulator Input |
| aut | AutoIt Script |
| autosave | GDevelop Autosave Data |
| avm | QAvimator Document |
| avrsln | Atmel Studio Legacy Solution File |
| aw | Free Pascal Archive |
| awk | AWK Script |
| awl | Alternative Web Language Source Code |
| Siemens AWL File |
| WebDev AWP Page Library |
| awp | WebDev AWP Page |
| awws | WebDev WebService Library |
| awx | Microsoft DirectX AWX Data |
| ax | Modula-3 Linker Information |
| axb | Alpha Five Xbasic Script |
| axd | ASP.NET Trace Handler |
| axe | Annotated XML Example |
| Paradigm C++ Integrated Debugger Data |
| axf | ARM RealView Compiler Object |
| µVision Absolute and Executable Object |
| axl | ASCET Compressed Model Data |
| axml | Xamarin Android XML Layout |
| axp | AxpDataGrid Data |
| GNU Arch Extension Data |
| axs | ActiveX Script |
| aya | Ayauhteotl Parser Data |
| azcli | Microsoft Azure CLI Script |
| b | BASIC Source |
| BuRg3r Definition Data |
| Limbo Source Code |
| Modula-3 Base Program |
| b1 | OpenEdge ABL Before Image |
| b2 | OpenEdge ABL Before Image |
| b24 | Ovation Pro for RISC OS C Script |
| b25 | Ovation Pro for RISC OS DDL Data |
| b26 | Ovation Pro for RISC OS Style Sheet |
| b27 | Ovation Pro for RISC OS Document |
| b2d | Brutus2D Source Code |
| b3 | OpenEdge ABL Before Image |
| b32 | Borland C Compiler Data |
| b36 | PDP-10 BLISS-36 Compiler Source Code |
| ba | BSC Intermediate Object |
| babylon | Babylon.js Scene |
| bacpac | Microsoft SQL Server DAC Exported Package |
| bal | B4A Layout |
| baml | Compiled XAML |
| bar | BREW MP Binary Application Resource |
| dBase Application Generator Menu Bar Object |
| bas | BASIC Source |
| basex | BaseX Data |
| bash | Unix Shell Script |
| baz | Zebra Printer Basic Source Code |
| bb | Blitz Basic Code |
| GCOV BB Data |
| bb2 | Blitz Basic Code |
| bbc | BBC Basic Source Code |
| bbf | ScriptBasic Compiled Binary File |
| bbg | GCOV BBG Data |
