Somebody can send you a link that proves a message or a card is theirs. Paste it below and this page does the checking, here on your device — nothing is uploaded, and it still works long after the message itself is gone.
The whole link, or just the part after the #. It is checked in this tab; nothing about it is sent anywhere.
Anyone can build a page that says “verified”. Paste the link here rather than trusting wherever it opens — and check the address bar says overheard-five.vercel.app.
A signature proves somebody held a key. Anyone can make a key and sign anything with it — including a message with your friend’s name in it. If you know which identity this should be, paste it here.
#, which browsers never send to a server. Not even this one sees it.