Gramblr is not working anymore, and seems to have shut down.
Here is a Gramblr alternative for posting to Instagram from a computer.
Here is how to upload pictures to Instagram from your computer:
Most browsers have a way of letting you change the way that a website shows to you. So even if you are on a laptop or desktop, you can have a website like Instagram show you the mobile version of the website. That is what we are going to do.
How to post to Instagram from Google Chrome
Uploading photos to Instagram from Chrome only takes a few clicks of the mouse.
Using Google Chrome, go to Instagram.com and sign in. Next right-click anywhere on the page and select Inspect from the list.
Part of the screen will be covered up with the Inspector tool, but we only care about the small icon of a tablet and phone, located in the top-left corner of the Inspector window. Click on it.
After, refresh the page.
Once refreshed, you should see the + icon to create a post on Instagram at the bottom of the window.
Once you are finished, click on the tablet/phone icon again. Close the Inspector tool and refresh the website to go back to the normal version of the site.
How to post to Instagram from Safari
On the top menu of Safari, go to Safari > Preferences > Advanced. Select the box at the bottom that show Show Develop menu in menu bar.
Find the option to enable Develop options in Preferences under the Advanced tab.
Next open a new Safari tab and click on Develop > User Agent > Safari — iOS — iPhone in the menu bar.
Next, go to Instagram.com and sign into your account. At the bottom of the screen will be a + icon — tap it and select a photo from your computer to upload. After the photo is uploaded, you can still apply filters and edit the photo as you would in the Instagram app.
When you’re done, make sure you change your user agent back to the Default setting to avoid viewing all websites in their mobile state.