Curtail is described as 'Curtail (previously ImCompressor) is a useful image compressor, supporting PNG and JPEG file types. It support both lossless and lossy compression modes with an option to whether keep or not metadata of images. It is inspired by ' and is an app in the Photos & Graphics category. There are more than 10 alternatives to Curtail for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and BSD. The best alternative is RIOT - Radical Image Optimization Tool, which is free. Other great apps like Curtail are ImageOptim (Free Personal, Open Source), pngquant (Free, Open Source), PNGGauntlet (Free) and Pingo Web Image Optimizer (Free).
Saving images for web/email/other media with the best compression ratio and quality is a difficult task if you don’t have the right tools. Choosing the right format then choosing the right parameters are the key factors of smaller files.
ImageOptim is excellent for publishing images on the web (easily shrinks images “Saved for Web” in Photoshop). It's useful for making Mac and iPhone/iPad applications smaller (if you configure Xcode to allow better optimization).
Experimental, fast Web PNG/JPG optimizer which offer lossless, visually lossless or lossy compression. it performs image reductions over iterations thanks to recursive multi-processing and multithreading systems.
Trimage is a cross-platform GUI and command-line interface to optimize image files via optipng, advpng and jpegoptim, depending on the filetype. All image files are losslessy compressed on the highest available compression levels.
OptiPNG is a command-line PNG optimizer that recompresses image files to a smaller size, without losing any information. This program also converts external formats (BMP, GIF, PNM and TIFF) to optimized PNG, and performs PNG integrity checks and corrections.
PngOptimizer compresses graphics files and removes extra, unnecessary data without affecting quality. It will update PNG files or converting BMP, GIF or TGA files to the PNG format using simple drag-and-drop.