There are many apps on the market that are great, however my one and only on-the-go tool is Snapseed, by Google.
This is a powerful app. I use it to prepare my pictures I upload to Instagram. And you can too.
From tuning the images, to cropping to right size for Instagram so they will upload without any changes, Snapseed makes it possible to have minimal loss of quality post-edit when uploading to Instagram.
Being rated as one of the top apps, its simplicity and ease of use, this app it’s a must have app, and now with the upgrade, you can apply quality filters.