Use cases

Hand off something of value

You're giving a $50 voucher to a friend — or a stranger who won your giveaway. Today that means hoping the email address you typed belongs to the right person. With handles on both sides, the transfer targets username.md/them: the issuer's system looks up the recipient's handle, checks the signature on the response, and delivers to the verified endpoint it finds there. The voucher goes to the person who controls that handle — not to a typo, and not to a lookalike who registered a similar-sounding email an hour ago.

The same pattern covers gift cards, tickets, credits, referral rewards — anything where "did this reach the right human?" is the whole problem.

Sell something to a stranger

Selling a guitar, a couch, a domain? The buyer's real question is never about the item — it's "is this seller real?" A handle answers with facts instead of vibes: verified claims (a domain proven by DNS, a bound Bluesky account, imported Keybase proofs) that anyone — including the buyer's AI agent — can check before money moves. Your reputation stops being trapped inside one marketplace's star rating and becomes something you carry with you, listing to listing, platform to platform.

Drop your handle in the listing. Serious buyers verify it in one request; scammers can't fake the signature.

Agents come to you — not the other way around

The old web made you go to every service and fill out the same forms, over and over, keeping dozens of profiles in sync by hand. The agentic web inverts that: software acting for other people fetches your handle — as JSON, Markdown, or a signed response — and gets your links, your keys, and your rules for how you want to be contacted. You publish once, on a name you control, and every agent that needs to know something about you comes and asks. Change a link once; every future lookup gets the new answer.

Your records, delivered to you

Think about how your medical records move today: from your provider to a third-party records vendor, through a portal you log into with yet another password, on terms set by everyone except you. A verified handle changes the destination. Because your handle publishes a signed, verifiable endpoint that provably belongs to you, an institution can release your records directly to you — encrypted to your published key, delivered to the endpoint you designated — with cryptographic proof that the recipient was really you. The middleman stops being a requirement and becomes a choice.

username.md is not a medical-records product and doesn't store health data. This is what the open primitives — did:web, published keys, signed endpoints — make possible for any institution that sends people their own documents: clinics, schools, banks, insurers, courts.

A win record is worthless if nobody can prove who won it

Agent arenas are here — fighting leagues, trading tournaments, coding battles, task marketplaces. Every one of them hands your agent a local account, a local ranking, a local reputation. Enter three arenas and you have three strangers who happen to share a name. A handle turns those scattered records into one provable track record: your agent registers as username.md/your-agent, proves control of the handle cryptographically, and its wins anchor to an identity no arena can reset — and no copycat can squat. Arenas get something too: one request tells them an entrant is real, so sybil entries and impostor personas fail at the door instead of corrupting the bracket.

And when the stakes rise — an agent betting, trading, or committing to an alliance — its operator can require a second signature on the big calls: autonomy where it's safe, consent where it counts.