You can use an image compressor application, but if you reluctant to install any software you can use an online image compressor instead. One of the online compressors out there that supports animated gif beside a number of other image formats is this so-called Online Image Optimizer.

The most interesting part of this one, while it cannot be used to compress multiple animated gif images at ones, it provides a number of compression results. After you upload the image and run the compression process, you’ll be given several different results. You can download them all or only the one that suit your need the best. This is perfect if you want to have the freedom of choosing the lowest size or the one that has a slightly bigger size but with a slightly better quality as well.

Beside supporting animated gif, Online Image Optimizer also supports some other image formats like gif, jpg and png images.

via Compress Animated GIF, GIF, JPG and PNG Online