A HastenOS extension ยท Settings
LinkLens always tells you when a link redirects, and where it ends up. Telling you whether that was a 301 or a 302 needs one extra Chrome permission, so it is off unless you ask for it.
The permission lets the extension observe the redirect status of the requests it makes itself. It is used for nothing else, and no browsing data leaves your device either way.
Results live in memory for the tab you analysed and are cleared when you close that tab or quit Chrome. Nothing is synced, and no URL you check is ever sent to HastenOS or anywhere else.
What each colour means, what dofollow and nofollow are counted from, which permissions are requested and why: all of it is written up on the extension's page.
Read the LinkLens page