Gifsicle is an open-source command-line tool for creating, editing and optimizing GIF images. It is commonly used for reducing the size of GIF files, as well as for adding or removing comments, frames and colors. Gifsicle supports most of the features of the GIF89a specification, and is highly customizable. It can be used to batch-process multiple GIFs, or to make minor edits to individual files. Gifsicle is available for Windows, Mac OS X and Linux systems.
Discontinued The program seems to be no longer updated. The latest version, 4.1, released in December 2015, can still be downloaded from the official website.
Warning The program is suspected of using your Internet connection for malicious purposes: https://www.reddit.com/r/videos/comments/1h5dnx/giffing_tool_is_available_for_download/
Discontinued The official website is no longer available. The latest version, 2.0, released in December 2011, can still be downloaded from Download.com.
Discontinued The project seems to be no longer developed. The latest version, 0.2.1, released in June 2013, can still be downloaded from SourceForge.