Reddit History viewer от PointySalt

Features
Hover Access: View history by hovering over any u/username link without opening new tabs.
Hidden Profile Retrieval: Access historical posts and comments using third-party archival data.
Multi-Window Interface: Open and drag multiple user history windows simultaneously.
Tabbed Navigation: Switch between Posts and Comments for the selected user.
Pagination: Load older interactions in increments of ten.
Avatar Display: Fetches the user's current Reddit profile picture.
Installation
This extension is currently installed via Developer Mode.

Download the code as a ZIP file and extract it to a local folder.
Open Google Chrome and go to chrome://extensions/
Turn on "Developer mode" in the top right corner.
Click the "Load unpacked" button.
Select the folder containing the manifest.json file.
Usage
Navigate to any Reddit thread. Hover your cursor over a username for one second to open the history window. You can drag the window by its header, toggle between posts and comments, and click specific items to open the original thread.

Disclaimer
This extension relies on the community-run Arctic Shift API. Functionality and uptime depend entirely on their servers.

License
This project is licensed under the MIT License. See the LICENSE file for details.