One Cat Viewer Free 5.0

The classic freeware image viewer reborn

For Windows 2000/XP/Vista/Win7

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In 1998 One Man And A Cat released one of the first thumbnail-based image viewers into the market. Its ease of use and quick thumbnail indexing prompted millions of downloads worldwide. By 2001 however, the number of image viewers had dramatically increased and One Cat Viewer went on a long hiatus. Five years later One Cat Viewer was completely redesigned and recoded. And now with version 5, an even sleaker, more flexible, and more powerful viewer is available. With the much more compact directory navigator, more room is available for thumbnails. A redesigned image cache provides the ability to quickly change between thumbnail sizes so you can "zoom" in and out on your directory to find the image you are looking for. And did I mention One Cat Viewer is free? No adware, no nag screens, no time limit. Free for personal or business use.

Powerful Features

  • Multiple thumbnail layouts (new in 5.0)
  • Fast thumbnail size switching (new in 5.0)
  • An array of image enhancement tools including redeye removal (new in 5.0)
  • Plays Video files (new in 5.0)
  • Vista Support (32 and 64 bit) (new in 5.0)
  • More image formats (such as Adobe Photoshop) (new in 5.0)
  • Fast Thumbnail Caching
  • Preview a sampling of each directory
  • Choose your thumbnail size and quality
  • Customizable colors and fonts
  • Resizable navigation, thumbnail, and image panes
  • Slide shows, fullscreen viewing, and zoom
  • Transition Effects in Slide Shows
  • Multi-level undo/redo
  • Lossless JPEG saving for many operations
  • Image conversion to JPEG, GIF, PNG, and more
  • Image printing, with print preview


Due to the considerable addition of functionality in version 5 of One Cat Viewer, a new compact toolbar has been created for quick access to the most common functions you perform while perusing through your photo collection. Navigation controls, slide shows, full screen mode, color and font customizations, zooming, and image transformations are all available. To pack in more functionality, many operations are now available as drop down toolbars. You can access these toolbars by clicking on the small arrows next to the toolbar buttons.

Navigation and Settings

Besides slide shows and simple navigation, you can change the colors, fonts,and zoom. A nice new feature of version 5 is the ability to change the layout of the viewer using the thumbnail layout dropdown.

Transforms and Enhancements

These 5 tool buttons pack quite a punch. Besides your basic rotations and flips, a whole array of single click image enhancements are available. All can be applied to the entire image or to the area of the image you select with the selection tools, so you can zero in on the problem. For power users, an advanced enhancements tool is available with histogram controls, custom filters, and more.

One Cat Viewer now plays Video!

Due to popular demand, video capability is back in One Cat Viewer. One Cat Viewer taps the power of Microsoft's Windows Media Player engine to display video right along with your images. Video will even play along with your slide shows! Thumbnails will show up right along with your images.

Of course you'll have to have the video player codecs installed to play the wide assortment of video formats out there. One popular option, and it is free as well, is to download and install the video codec pack K-Lite Video Codec Pack. During installation, make sure you place a check beside the thumbnail creation support option so that One Cat Viewer can properly create the video thumbnails.

Fast Sampling Mode

One Cat Viewer can now be placed in a Sampling Mode, which chooses a small number of images distributed throughout each directory and only shows those thumbnails. Its easy to turn off and on and is indespensible in searching through large image collections quickly, getting a solid idea of what is in each directory without having to scroll through them. This is one addictive feature you will not know how you did without!

Image Conversion

Need to convert an image into another format? One Cat Viewer can handle that. Images can be saved in the JPEG, GIF, PNG, TGA, PCX, or BMP formats. You can also resize its dimensions. When saving as a JPEG, Viewer provides valuable hints on quality and smoothing settings.

Free Updates

One Cat Viewer is a pet project of mine. Version 4 began a new era for the image viewer and with version 5 I hope to continue updating One Cat Viewer Free with new features, as well as further streamlining its functionality. Check back often, afterall it is freeware and you might as well have the latest and greatest. See a feature you'd like to see, drop an email.

Version History

VersionReleaseChanges and Additions
4.003/29/2006 Reintroduction of One Cat Viewer, after years of slumber.
  • Sample Mode allows display of a distributed sample of thumbnails per directory.
  • Transition effects to spice up full screen slide shows.
  • Option for one click full screen shows added.
  • Multi-level Undo/Redo for many operations.
  • Complete redesign of the UI
  • Multiple thumbnail layouts
  • Fast thumbnail size switching
  • More image enhancement tools and redeye removal
  • Plays Video files
  • Vista Support (32 and 64 bit)
  • Support for more formats (such as Adobe Photoshop)

Download Free Viewer

Copyright (C) 2012 Keith Leinenbach   -   One Man And A Cat Software