Graphics Workshop for Windows thumbnail file
File type: Bitmap image file
A .thnl file is a thumbnail file used by Graphic Workshop Professional for Microsoft Windows.
It contains thumbnail image data for displaying a preview of an image within the software.
File type category:
Bitmap image file
Date updated: September 27, 2026
Graphic Workshop Professional is an image-management and graphics utility for Microsoft Windows. Its THNL file extension identifies files that store thumbnail previews associated with images handled by the program.
A THNL file is intended to support the software's thumbnail or catalog views rather than serve as a general-purpose image file. It may therefore be used together with the original image files and is not normally the primary copy of an image.
Graphic Workshop Professional was developed by Alchemy Mindworks.
Open a THNL file with Graphic Workshop Professional for Microsoft Windows, the program associated with this file type. The file may be intended for use by the program's thumbnail or catalog features rather than for direct opening as a standalone image.
If Graphic Workshop Professional is unavailable, a THNL file may not open correctly in modern image viewers. The original image associated with the thumbnail is usually the more suitable file to open.
THNL files are software-specific thumbnail files and are not commonly exchanged as standalone images.
To obtain a standard image, open the original image associated with the thumbnail in an image editor and export it to a supported format. Converting the THNL file itself may not recover the original image.
Software applications that can open thnl files:
Microsoft Windows
Software apps that create thnl files:
Microsoft Windows
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