FotoFox is a free app for iOS/ Android which can compress the photos and videos you take by up to 90%, saving a vast amount of space, while still giving you access to the high quality originals.
The app looks very basic, with the absolute minimum of options. Select Photo or Video, tap a button to take the shot/ start recording, tap again to stop.
The clever part happens next: FotoFox (almost) instantly compresses the picture/ movie, reducing its quality but cutting its size by up to 90%, while uploading the original to its own private server. No need to register first, set up an account or anything else: it just works.
You're then able to view or share the optimised version in the usual ways, which should be much faster as it's now so small. But if it's something important then you can download the original version when necessary.
There's also an option to process the photos and videos already on your device, an easy way to free up even more space.
FotoFox is easy to use and works as described, typically saving around 80% on our test photos/ videos.