Snapseed ( Android & iOS )
It is a free app on the Playstore as well as iTunes. The best thing about Snapseed is the number of controls it gives you to play around with your photograph.
There is an option of ‘Curves’ which lets you alter the RGB tones in the pictures, this is a hard to find feature in editing apps. Also, Snapseed doesn’t degrade the quality of pictures much. ‘Enhance’ tool automatically scans the face in the photograph and brings the focus on it by increasing spotlight, smoothening skin and clarity of the eyes. There is an amazingly helpful option to save ‘your look’ i.e, save all the edits you did on a picture on the app so that you can just select this look later and save time. Snapseed is more of a pro editing app, so if you don’t want too much control to confuse you then I suggest you use a simpler one.
VSCO ( Android & iOS )
VSCO is the app you need if all those pictures with amazing unrealistic tones on Instagram fascinate you. The filters available on VSCO are unmatched. You also get other basic tools such as cropping, exposure, contrast as well as advanced tools like grains, tint, shadow tint etc. Just like Snapseed, VSCO allows you to copy-paste your edits from a previously edited picture to another new one. VSCO community is filled with talented creative heads, make sure to sign up to have your own account where you can post your pictures and follow others for inspiration.