There are hundreds of Tumblr compatible applications and web sites. Some of them require extra permission to access features like your Dashboard, Following, Likes, or to create posts. When this happens, you'll be prompted to "Grant this application access to your Tumblr account".
Permission will either be for read and write or read access. Read and write access permits the application or web site to create and edit your posts.
You can revoke access at any time from your Preferences page in the Apps area.
Since we didn't build (and don't have access to) these applications, Tumblr can't support them. Please contact their creators with any support inquiries.