What is the RBZ file format?
An .rbz file is a SketchUp Ruby Extension Archive - the standard distribution format for plugins and extensions for SketchUp, Trimble's 3D modeling application. Introduced in SketchUp 8.0 (2010), the format replaced the practice of distributing loose .rb Ruby script files, giving developers a single installable package.
Internally, .rbz is a standard ZIP archive renamed with a different extension. Renaming an .rbz file to .zip allows inspection or extraction with any ZIP-compatible tool such as 7-Zip or Windows File Explorer. The archive must contain a root-level .rb loader file and a support folder of the same base name; the loader script holds the extension's metadata - name, author, and version string.
Installation is straightforward: in SketchUp, open Window → Extension Manager → Install Extension and select the .rbz file. Extensions are also distributed through the official Trimble Extension Warehouse (extensions.sketchup.com) and the community Sketchucation store, both of which enforce a standard manifest structure before publishing.
Because .rbz is ZIP-compatible, it uses per-entry DEFLATE compression and CRC-32 integrity checks. Files range from a few kilobytes for simple tools to tens of megabytes for extensions that bundle textures, models, or compiled libraries.
Security & safety
RISK: MEDIUMRBZ files contain executable Ruby code that runs inside SketchUp with full Ruby API access. Only install extensions from trusted sources (Extension Warehouse, SketchUcation). Malicious extensions could access the file system. Inspect scripts by extracting the ZIP if in doubt.
Format details
in a nutshellPrograms that open RBZ files
Windows3 apps
7-Zip
Open-source Right-click → Open archive (or rename to .zip first) to inspect the Ruby scripts inside. 
SketchUp (Extension Manager)
Freemium Window → Extension Manager → Install Extension → select the .rbz file. SketchUp installs and activates the plugin. 
macOS2 apps
SketchUp (Extension Manager)
Freemium Window → Extension Manager → Install Extension → select the .rbz file. Technical details
deep spec| Internal format | ZIP archive (PKZIP-compatible, renamed extension) |
| Magic bytes | 50 4B 03 04 - standard ZIP local file header (PK signature) |
| Byte order | Little-endian (ZIP structures) |
| Compression | DEFLATE per entry (ZIP standard) |
| Encryption | None within the RBZ wrapper |
| Typical file size | 10 KB - 50 MB (most extensions under 5 MB) |
| Required structure | Root .rb loader file plus a support folder of the same base name |
| Integrity check | CRC-32 per ZIP entry |
| Max entries | 65,535 (ZIP format limit) |
| Embedded file encoding | Ruby script (.rb) files are UTF-8 plain text; binary assets also permitted |
| Supported OS | Windows, macOS |
| Installation method | SketchUp Extension Manager: Window → Extension Manager → Install Extension |
| Distribution platforms | Trimble Extension Warehouse (extensions.sketchup.com); Sketchucation store |
| Inspection | Renaming .rbz to .zip allows extraction with any ZIP-compatible tool |
| Released | 2010 (SketchUp 8.0) |
| Latest version | no format versioning; current SketchUp 2024 still uses RBZ |
| Specification | ruby.sketchup.com |
RBZ conversions
Community Q&A
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