You can use one video cutter free from this list, which contains 11 different options. However, there are mainly used to cut videos. Some come with ability to merge videos from the same source or from other files. If you just want freeware, I think most free online video joiners can work.
Now back to talking about myself, I use Joyoshare video joiner to combine unlimited video files, which at the same time can cut videos easily. However, it's low-budget with a free trial version.