ACO file: How can I open a .ACO file?
The table below provides useful information about the .aco file extension. It answers questions such as:
- What is the .aco file?
- What program do I need to open a .aco file?
- How can the .aco file be opened, edited or printed?
- How can I convert .aco files to another format?
We hope you find this page helpful and a valuable resource.
✅ Adobe Photoshop Custom Swatch

The ACO file is an Adobe Photoshop Swatch. ACO file is used in Photoshop as a set of colors named a swatch. Adobe Photoshop is a graphics editor published by Adobe Systems. It is the market leader for commercial image manipulation.
✅ CYANA Dihedral Angle Constraint File

The ACO file is a CYANA Dihedral Angle Constraint File. CYANA is a program for automated structure calculation of biological macromolecules on the basis of conformational constraints from NMR.
✅ ArCon Object Collection

The ACO file is an ArCon Object Collection. ArCon (planTEK) is a modern planning and design software for architects.
⚠ Be careful with .aco files.
It's important to know that the .aco file extension can be used by various programs, not just the ones you expect. This includes potentially harmful software or malware that might create .aco files. Be cautious when dealing with .aco files from unknown sources.
🚫 The .aco file extension is often given incorrectly!
According to the searches on our site, these misspellings were the most common in the past year:
Is it possible that the filename extension is misspelled?
We found the following similar file extensions in our database:
🔴 Can't open a .aco file?
When you double-click a file to open it, Windows examines the filename extension. If Windows recognizes the filename extension, it opens the file in the program that is associated with that filename extension. When Windows does not recognize a filename extension, you receive the following message:
Select an app to open this .aco file
It means that the operating system does not have a default app associated with the .aco file type. To resolve this issue and open the file, you can take the following steps:
- Right-click on the .aco file. A context menu will appear.
- From the context menu, select Open with. Windows will display a list of recommended apps.
- If the desired app is listed, select it from the provided options.
- If you cannot find the appropriate app, you may need to install software that supports the specific file type.
If you don't know how to change the default app for the .aco file, check the FAQ.
🔴 Can I change the extension of files?
Changing the filename extension of a file is not a good idea. The extension of a file serves as a hint to the operating system and various software programs about the type of data contained within the file. When you alter a file's extension, you essentially modify how software applications interpret and handle that file. Every file has a specific format, also known as its file type or file format. The problem is, changing the file extension does not change the file format.
If you have helpful information about the .aco file extension, write to us.