Clipboard2File (Upload From Clipboard) by Clipboard2File

This extension will NOT work until you set dom.events.asyncClipboard.clipboardItem to true in about:config! The Clipboard API is fairly new so not every part of it is enabled by default (for now)
https://developer.mozilla.org/docs/Web/API/Clipboard_API#browser_compatibility


Clipboard2File is very useful for websites that don't natively support pasting images. Don't worry about temporary files or filling up your computer with junk images you'll only use once!!!

Permissions explained:

• Access your data for all websites: This is a key permission, because the functionality of Clipboard2File is implemented as a content script that must be placed inside each website. Clipboard2File is lightweight and heavily performance tested. It won't slow you down!
• Get data from the clipboard: This is required to offer the key feature of Clipboard2File. It must read your clipboard to see if there is an image on it.
  
• Input data to the clipboard: This is required to offer the ability to clear your clipboard after pasting.

Clipboard2File is less than 100 lines of code. You can read the source code here. You can also use CRX Viewer to verify that what you download is identical to the code on Github!