This site hosts a personal Microsoft Word add-in: six editorial modes (continuity, line edit, copy edit, proofread, comment execution, redline summaries) that run on the author's own Anthropic API key.
The entire application is one static file: taskpane.html. It stores the API key in the pane's local storage and sends every request directly to api.anthropic.com — this server only delivers the page.
To install it in Word, you need the manifest.xml that was delivered alongside this page, not anything here.