What is the CAPX file format?
.capx is the compressed project archive format for Construct 2, a 2D game development tool created by Scirra Ltd. Despite the custom extension, a .capx file is a standard ZIP archive - renaming it to .zip reveals its contents in any archive utility.
The archive root contains a project.caproj or project.c2proj XML descriptor holding the project's name, version, and global settings. Event sheets (the game's visual logic layer) are stored as XML files, as are layout definitions and object configurations. All imported assets - images, sounds, fonts - are embedded directly in the archive, making .capx a fully self-contained, portable package. Per-entry DEFLATE compression and CRC-32 checksums are provided by the ZIP container.
Construct 2 reached end of life in July 2021 when Scirra stopped selling licenses. Construct 3, its successor, uses the .c3p format and includes a built-in importer to convert .capx files. The earlier uncompressed Construct 1 format used the .cap extension and is not directly compatible with Construct 2 projects.
Security & safety
RISK: LOWCAPX is a ZIP of project files (XML + assets). It does not execute code directly. Some CAPX game templates from third-party sites could theoretically bundle malicious scripts that run when the game is exported and played, but not on opening the file itself in the Construct editor.
Format details
in a nutshell- Capella music notation (alternative CAPX) - Capella (music notation software by capella-software AG) also uses .capx for its compressed project files - completely unrelated to Scirra Construct.
Programs that open CAPX files
Windows3 apps
7-Zip
Open-source Right-click CAPX > Open archive - browse internal XML files and assets (read-only inspection). 
Construct 2 (Scirra)
Freemium File > Open > select the CAPX file. Free (personal) edition opens existing projects; paid license needed to export.
Construct 3
Freemium Menu > Import Construct 2 project - imports CAPX and converts to Construct 3's C3P format. 
macOS1 app
Construct 3 (browser-based)
Freemium Open Construct 3 in Chrome/Safari; Menu > Import Construct 2 project. 
Linux1 app
Technical details
deep spec| File type | ZIP-based game project archive |
| Developer | Scirra Ltd |
| Container | ZIP archive (PKZIP format; rename to .zip to inspect) |
| Compression | DEFLATE per ZIP entry |
| Integrity | CRC-32 checksum per ZIP entry |
| Magic bytes | 50 4B 03 04 at offset 0 - standard ZIP local file header signature |
| Project descriptor | project.caproj / project.c2proj (XML) at archive root |
| Event sheet format | XML (Construct 2 condition-action game logic) |
| Typical file size | 100 KB - 500 MB (depends on embedded image and audio assets) |
| Maximum archive entries | 65,535 (ZIP specification limit) |
| Platform | Windows (Construct 2 IDE was Windows-only) |
| MIME type | application/zip |
| Superseded by | .c3p (Construct 3 project format, from 2017) |
| Product status | Construct 2 end-of-life July 2021; Construct 3 can import and convert .capx files |
| Asset storage | All images, sounds, and fonts embedded directly inside the ZIP archive |
| Released | 2011 (Construct 2 r1) |
| Latest version | Construct 2 r280 (final release, 2019) |
| Specification | www.construct.net |
CAPX conversions
Community Q&A
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