GIFmicro is a free tool which rewrites GIF files to reduce their size.

The program looks great. There's a sleek, black interface, panels slide out smoothly while flat buttons carry out its main actions.

Getting started is as simple as hitting the add button and choosing your source images (or just dragging and dropping them onto the program).

Tapping the Options icon shows various compression settings. You can enable/ disable interlacing, reduce the number of colours, maybe resize the image to a fixed resolution.

There's also good control over the name and location of the destination files, with options to rename them, save them to a new folder, overwrite the originals, and more.

The default lossless compression made little difference to our test GIFs, unsurprisingly. Many were unchanged, the rest reduced by only a few bytes.

Cutting the number of colours in the image makes much more of a difference, saving 50% or more, but also reduces image quality. You'll need to experiment to see if this is acceptable, and what the right levels are for you.