You can use UnFREEz to merge different GIF files and create an animated one. This one is a portable product and you don`t have to install it. You don`t have to fear that your Windows registry entries will be affected because it is not the case and you can use this one with an external device. The interface of this one is pretty simple and the options are quite limited. Simply drag & drop one or multiple GIF files and then press the Make Animated GIF button so that they can merge into a single animated image. The application supports only GIF images, so if you have JPG or PNG, save them as GIF and then add them onto the interface.
After you added the frames you will need to input the delay time to use between frames. The time will be in centiseconds (1/100th of a second) which means 100 centiseconds will be 1 second. You can also enable the loop animation option and view the information on the right side of the window. This program works fast and it will complete your task in a matter of a few seconds.
This UnFREEz won`t give you any errors and you will see that it works pretty well. The resulted GIF will play in any web browser.
UnFREEz is licensed as freeware for PC or laptop with Windows 32 bit and 64 bit operating system. It is in image processing category and is available to all software users as a free download.