I used PNGCrusher 1.2, pngCrushrrr 1.0 and pngcrushX 1.0 on an 84K PNG file that I made in Adobe Photoshop. All three programs reduced the file size to 32K. With all three programs, the quality of the reduced image was pretty the same as the original to the eye.

--- PNGCrusher 1.2 did one thing I didn't like: It replaced the original file without any warning. It gave the reduced file the same name as the original. The new file was saved in the same place as the original file. The author should at least include a short Read Me with the program, so that users are aware of this "disappearing act". PNGCrusher took about 7 seconds to crush the file.

--- pngCrushrrr 1.0 did not replace the original file. It created a new file, and appended ".crushed" to the file name, before the ".png" extension. The new file was saved in the same place as the original file. pngCrusherrr also took about 7 seconds to crush the file.

--- pngcrushX 1.0 operated a little differently. Unlike the previous two, this last program placed a larger window on my screen, and actually showed me as it ran through 124 different compression methods, and selected the one which resulted in the smallest file size. pngcrushX created a brand new file, which it named "crushed.png". Unlike the first two programs, which save the new file in the same place as the original, pngcrushX saved the new reduced file to the desktop. A warning about pngcrushX: If you remove the program and the Read Me file from the .dmg image, and place them in a folder, make sure that the folder is named exactly "pngcrushX"; otherwise, the program will spit out an error, and will not run. pngcrushX took about 53 seconds to crush the file.

--- pngCrusherrr is the overall winner: Short crushing time, doesn't replace the original, and doesn't butcher the file name, just appends to it.