Actually, some people would think that Google Photos is a perfect solution. Free unlimited storage for life! I uploaded more than 5000 photos via WiFi in Asia last year - It allowed me to free up space and organize the photos (by location, person, album, contents, etc.)
The app is free and the only real prerequisite is having a Google (e.g., Gmail) account. Give it a try with the existing photos on your phone - you don't need to delete them from the phone or other tools if you don't want to. Do give the batch processes a few days to do the initial indexing to see the real magic. After a couple of days, wander through all of the menus in the app (or login to photos.google.com on your computer).
In the hopefully unlikely event that your phone is nearly full before freeing up space, take these additional steps:
https://support.google.com/photos/answer/6128843?co=GENIE.Platform=iOS&hl=en
Two important notes:
- Only use the 'garbage can' in Google Photos to Permanently delete photos that you do not want - Use "Free up space" or "Delete device copy" to free up space on your phone.
- (Assuming normal settings), Android devices back up new images as soon as you connect to WiFi, iOS devices only begin backing up when you connect to WiFi and open the app.
It is important to use and understand any non-trivial app (Maps, Cloud Storage, etc.) prior to using it in the field.
Finally, if your experiment with Google Photos on your phone is successful, you will probably subsequently want to install the Google Photos Desktop Uploader (
https://photos.google.com/apps) on your Mac or Windows computers. I uploaded tens of thousands of images which I previously stored on external drives.