What Is an ACT File?
If it’s not used with Photoshop, you may instead have an ADPCM compressed audio file.
Alma CAD/CAM documents use the ACT file extension, too.

ACT Files.
These store instructions that 3D cutting machines use to understand how something should be cut.
ACT is also the abbreviation for some tech terms that are unrelated to these file formats.
Some examples includeaction tracking, automatic code translation, account contact tool, andaccess charge terminal.

How to Open an ACT File
Adobe Color Table files can be opened withPhotoshop.
pick the small menu button in the top right corner of theColor Tablesection.
In there, chooseLoad Color Tableto browse for the ACT file.
This menu is also where you create an ACT file to save the prefs for later use.
Just pick theSave Color Tableif you want to do that.
You should also be able to open an Adobe Color Table file withAdobe Illustrator.
ACT files that are Alma CAD/CAM documents can be opened withAlmacam Space Cut,Almacam Weld, andAlmacam Tube.
Genesis3D Actor files are 3D characters created withGenesis3D.
That program can open these types of ACT files, but so should Autodesk’s3ds Maxand chUmbaLum sOft’sMilkShape 3D.
The file is used to store a game action like playing sounds or showing graphics.
They’re typically stored with ACTX files, which serve as a description for the action.
Microsoft’s discontinued Visual FoxPro is used to open FoxPro Documenting Wizard Action Diagram files.
If that’s the case, seeHow to Change File Associations in Windowsfor help changing it.
The other file formats abovecan, you just probably can’t use afile converterto do it.
Still Can’t Open It?
This is really easy to do since so many file extensions are spelled similarly.
Unfortunately, a similar suffix doesn’t necessarily mean similarities in format.
Several other examples could be given, like ACC and ATT.