Gramblr is a handy application that lets you upload photos to your Instagram account right from your desktop computer. It includes all the needed features that you could require so that you won't feel any difference between the usual method of uploading photos to Instagram with your smart phone and using this tool. This means that Gramblr also lets you edit the photos and caption them before the actual upload.
Gramblr lets you apply effects and filters to photos, rotate them, crop them, flip them, draw over them, and caption them right before uploading them. You can upload them right away or you can postpone their upload to a later, scheduled date and time. Gramblr also requires you to sign in using an Instagram account when starting it, but this is not a real problem. On the other hand, the fact that it requires you to upload only JPEG/JPG images, and only of 500 KB in size might be a real problem. Gramblr is otherwise a really nice tool but this limitation is quite annoying. Moreover, not all the usual, fancy Instagram filters are also available when using Gramblr.
Cutting long story short, I still like Gramblr despite its flaws, especially since it's free and really easy to use. I think it's worth a shot whenever you need to upload photos to Instagram using your computer.