Repostlr - Repost for Tumblr

Repostlr = Repost + Tumblr
Repostlr makes it easy to repost media from Tumblr

How to repost media to Instagram from Tumblr
Open Tumblr app and use Share Menu
Copy Link
Paste URL in Repostlr  and your media can now be reposted to Instagram

How to upload GIF to Instagram from Tumblr 
Instagram allows only photos and videos to be posted but using Repostlr you can convert the GIF to video and repost.
Open Tumblr app and use Share Menu
Copy URL for GIF media
Paste URL and GIF will be converted to Video and can be reposted to instagram