This is an app I think I paid for if I remember rightly, I can't exactly remember how much it was though. I didn't used to use this app before because I used to fully edit my photos so there were no need in using or even having this app. I use facetune for whitening my photos, now when I say whitening my photos, I don't mean whitening them fully, I mean whitening the backgrounds of them because they're usually taken on my bed or with a white wall behind. All you do is select the whitening tool, zoom in to where you want to whiten it and then move your finger over that bit but be careful not to go over the items/products that you don't want whitening. That's the only problem with using facetune to whiten.
This app I have had for the longest time but recently they changed it where you had to have an account or be signed in which is the only frustration I have found with the app. I use this app for the flip tool. You see, when it comes to taking 'selfies', I take them on the actual iphone camera because I feel like the snapchat camera murders the quality of the photo. When you take a photo (with the front facing camera), it flips the screen whereas snapchat doesn't. Therefore I use picsart to flip the photo back to it's original state.
I use this app for seeing how my Instagram feed will look like. This app has the grid so you can see how your feed will look when you upload the photos to Instagram. You can switch and rearrange photos on there until you like how it all looks. i think it's a great app considering it was free and for other apps like this, it would probably cost you at least 99p.
That marks the end of my three favourite editing apps, hope this gave you some insight in to how I would edit my photos and what I prefer for my photos.