Mastodon Hashtag Helper

About

Mastodon Hashtag Helper is a browser extension that watches what hashtags you use when posting on Mastodon, remembers them, and surfaces them as clickable buttons directly inside the Mastodon compose form so you can reuse them without typing.

All data stays entirely on your machine — no network requests, no tracking, no external services.

The extension does not run on every website by default. It uses optional host permissions, meaning it starts with no access to any page. You grant it access per site through the popup.

When you click the extension icon, the popup reads the hostname of your current tab and shows a toggle switch. Flipping the toggle on triggers the browser's native permission dialog asking if the extension can access that specific site. If you approve, the extension stores that grant and will automatically inject itself on future visits. You can revoke access per-site at any time from the same popup, which also shows a full list of every approved domain.

This per-site model means the extension only ever touches Mastodon instances you've explicitly trusted.

This code was written with help of AI tools