MP4Tools is an open-source package which includes two separate applications for manipulating MP4 files.
MP4Splitter enables splitting a target MP4 file into multiple files, without re-encoding. The program displays a preview of the video and allows you to select the individual split points within the clip. You can then export them with a click.
MP4Joiner joins multiple MP4 files into a single video, again without re-encoding. Drag and drop your source files, reorder them if necessary and export the results when you're ready.
Options include a setting to force the reencoding of your video, and allow you to choose your preferred quality setting. This might be handy if you're creating clips to share with others - individual scenes from a video, for instance - and would like the files to be as small as possible.
What's new in v3.5:
* MP4Joiner: fixed some bugs
* updated MP4Box to version 0.7.2-DEV-rev5
* updated ffmpeg to version 3.2.4
* added Polish translation (thanks to Andrzej Rudnik)
MP4Splitter and MP4Joiner worked for us, splitting and joining videos as required, and with the minimum of hassle.
There are some small issues - we'd like to be able to drag and drop MP4Joiner files to reorder them, rather than clicking buttons - and we're not really sure why MP4Splitter and MP4Joiner are being distributed under a single "MP4Tools" banner when they're entirely separate applications. But we like them both anyway, and it'll be interesting to see if the developer adds other tools in future.