What is the APS file format?
An .aps file is a binary intermediate cache generated automatically by the Visual Studio resource editor when a developer opens or edits a .RC resource script in a Windows C++ project. It stores a compiled binary snapshot of the project's Windows resources - dialogs, menus, icons, string tables, accelerators, and version information - allowing the IDE to load the resource editor quickly without re-parsing the text source each time.
The .aps format is a flat binary serialisation in little-endian byte order, proprietary to the MSVC toolchain. It contains the same resource data as the .rc file but stripped of comments and symbolic name references, which are kept separately in resource.h. The .aps file is regenerated from .rc automatically whenever the resource editor is opened, making it a true derived artifact with no role in command-line or CI builds.
Developers should exclude .aps files from version control by listing them in .gitignore; only .rc and .res files need to be tracked. Deleting an .aps file is always safe - Visual Studio recreates it at the next resource editor session.
The standard pipeline goes: .rc source → Resource Compiler (rc.exe) → .res binary resource object → linker embeds into the .exe or .dll. The .aps file is a side-effect of the IDE and plays no part in this chain.
Security & safety
RISK: LOWAPS files contain compiled Windows resource data (dialogs, strings, icons) and no executable code. They are safe to delete. The only risk is if an .aps file from an untrusted project contained an embedded malformed resource, which could theoretically trigger a bug in the resource compiler/editor, but this is a negligible real-world risk.
Format details
in a nutshell- AVR Studio Project File - Atmel AVR Studio (now Microchip Studio) uses .aps for microcontroller project files; unrelated to Visual C++ resource files.
- Microsoft Access Settings / Snapshot - Some older Microsoft Access versions used .aps for saved wizard or snapshot settings.
Programs that open APS files
Windows1 app
Microsoft Visual Studio
Freemium Visual Studio opens .aps automatically via its resource editor - you do not need to open it directly. If needed, use File > Open to inspect it, but normal workflow never requires this. Technical details
deep spec| Role in build pipeline | IDE cache only; not consumed by `rc.exe`, linker, or CI builds - purely a Visual Studio resource editor artifact |
| Source file | Compiled from the project's `.rc` resource script by the Visual Studio resource editor |
| Output file | The actual linked resource is the `.res` binary produced by `rc.exe` from `.rc`; `.aps` is not the compilation output |
| Byte order | Little-endian (Windows x86/x64) |
| Content | Binary-encoded dialogs, menus, icons, bitmaps, string tables, accelerators, and version info |
| Non-symbolic | Comments and symbolic name references from `.rc` are stripped; symbols are stored separately in `resource.h` |
| Regeneration | Automatically recreated from `.rc` by Visual Studio; safe to delete at any time |
| Version control | Should be excluded via `.gitignore`; only `.rc` and `.res` files should be committed |
| Compression | None (flat binary structure) |
| Partial signature | Some `.aps` files begin with `00 00 00 00 20 00 00 00 FF FF`; no universal constant signature is documented |
| Platform | Windows only (MSVC toolchain) |
| String encoding | Resource strings may be UTF-16 LE (Unicode resources) or ANSI depending on resource type |
| Released | mid-1990s (Visual C++ 2.x / early MSVC IDE era) |
| Specification | learn.microsoft.com |
APS conversions
Community Q&A
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