Instagram doesn't allow automatic posting, so we push your photo to your phone and open it in the Instagram app. We do everything we can to make the process as easy as possible but any service that posts automatically is in Violation of Instagram's Terms of service. The final step of posting still has to be done by you.
We do not store your username and password.
The best image size is 640x640px as this is what Instagram uses.
You can upload any image size and we'll do our best to size it for Instagram for you. Images that are not square have white bars added to the sides to make them square. You can then use the crop tool to choose what you want to send to Instagram.