Photo shrinking programs / apps at no cost

[Kenk]

are there any great options out there to shrink photos down that work well? / at no monthly cost? I periodically want to upload photos, but struggle with the size constraints
Thanks folks!

[sqlbullet]

MacOS - Preview.app (included)
Windows - Photo app (included?)
Linux - imageMagick (sudo apt-get install imagemagick)

[Kenk]

Thanks, already on my iPhone or something I need to get from the App Store?

[sqlbullet]

The photo app installed by default include tools for resizing an image.

Launch Photos
Select the photo
Click "Edit"
Click the "Crop" icon
Click the "Dimensions" icon
Edit dimensions and save.

That said, as a general rule image editing is best left to an actual desktop/laptop computer, not a mobile device.  Mobile devices are largely architected to be content viewers, not content manipulators.