When digging for reference images to use for studies I came across a photo I rather liked the colors on and wanted to use for pallet inspo and then I thought, hey I can use one of those pallet generators and that lead me to investigating the features of what I found.
https://palettegenerator.com/
This lets you upload one or more images to create pallets from, and it auto generates up to 10 colors. Pretty straight forward, nothing fancy and no account needed.
https://www.canva.com/colors/color-palette-generator/
This lets you upload an image and you get 4 colors, that's it, no adjustments. The service itself seems to be for a sort of.. web-based in-design service which is pretty cool if you need it but I don't at this time so I didn't look into it further than that.
https://coolors.co/
This one one though, frankly surprised me at just how many options it had. First, you can manually choose exactly where from the image your pallet generates colors from. While it has a limit of 5 colors, you can do a whole lot to manage these colors.
Then it has a whole bunch of adjustment features, such as seeing what your pallet looks like in the different colorblindness types.
And the different shades of a particular if you wish to adjust it. Also usual stuff such as hue, saturation, brightness, and temperature adjustments for the whole pallet.
And a cute little feature is the ability to see what the closet Copic and Prismacolor version of these colors, are, which can be useful.
All of this without having to make an account! And honestly this site is what prompted me to document what the other sites had in the first place just because of how much it stood out to me in comparison.