To create a GIF animation from multiple images, using an online service is obviously the simplest way, you don’t need to download or install anything, and they work on all operating systems including Windows, Mac, Linux, and you don’t need to pay for it.
1. Make a GIF online
You can make a gif online with this handy site: http://gifcreator.me/, it supports many input image formats: jpeg, png, bmp, gif and psd.
You can also set the image size and animation speed easily with a few clicks.
2. Join multiple gifs online
3. Crop and resize a gif online
You can crop, resize, optimize a gif in one step with http://resizeimage.net/.