.ora File Extension

What kind of file is an .ora?

An .ora file is an OpenRaster layered image. It is designed for moving editable raster artwork between applications rather than locking the project to one editor. The de facto image/openraster MIME type identifies the format, although it is not currently registered by IANA.¹²

OpenRaster is a ZIP container. A conforming file has stack.xml describing the canvas and layer stack, image data such as a PNG for each raster layer, a Thumbnails/thumbnail.png preview no larger than 256 by 256 pixels, and a flattened mergedimage.png.³

The outer magic bytes are normally the ZIP signature 50 4B 03 04, but that signature is shared by many formats. For a reliable check, verify that the archive's first entry is an uncompressed file named mimetype whose exact contents are image/openraster, with no whitespace or newline.³

How do I open an .ora on my computer?

Use an editor with explicit OpenRaster support:

• Krita opens and saves .ora files on Windows, macOS, and Linux.
• GIMP imports and exports OpenRaster on the same desktop platforms.⁴
• MyPaint and Scribus also support the format.¹

Web browsers and standard photo viewers generally do not open .ora directly. If you trust the file and only need to see the finished composition, inspect the ZIP container and open mergedimage.png. Work on a copy, and keep the original when its editable layers matter.

Poly support for .ora

Poly stores, syncs, shares, versions, and finds .ora files by name and basic file properties. It does not currently unpack the OpenRaster container, generate a thumbnail, preview the composite, index layer names or pixels, create visual-search data, or make the artwork available to the Poly agent.

Download the original and use Krita, GIMP, or another compatible editor to view or change it. This is Storage Only support because the file remains manageable in Poly without format-aware processing.

History of .ora

Boudewijn Rempt and Cyrille Berger proposed OpenRaster in 2006. They modeled its transparent ZIP-and-XML structure on OpenDocument and intended it for layered-image exchange between editors.¹ The published OpenRaster specification is version 0.0.6.

The format separates interchange from editor-specific project storage. Its baseline defines features that applications can share, while extensions can carry additional behavior. A viewing-baseline reader may show the required flattened image even when it cannot safely edit every layer feature.⁵

Working with .ora and alternatives

Choose the destination according to what must survive:

Krita notes that storing separate PNG layers can make OpenRaster files relatively large, so .ora is not intended as a web-delivery format.⁶ Export PNG, JPEG, WebP, or AVIF for delivery, but keep the .ora source if you may need to revise individual layers.

Treat unfamiliar ORA files as untrusted archives. Use maintained software, and remember that hidden layers and layer names may contain sketches, notes, or other material absent from mergedimage.png. Review the complete layer stack before sharing an editable source.