Mark

Start a purchase of prepaid stamps for your key (requires API key). Returns `url`: a Stripe Checkout link that a PERSON must open and pay; you cannot pay it yourself. Show the link to your user, then poll get_balance. The stamps land on this key's account and never expire. Packs: 5 for $1.00, 10 for $1.50, 50 for $5.00, 100 for $8.00, 500 for $35.00, 1,000 for $65.00, 2,000 for $120.00 (bundle ids bundle_5, bundle_10, bundle_50, bundle_100, bundle_500, bundle_1000, bundle_2000).

Provision a persistent API key with no human, browser, or email in the loop. Call this once, store the returned `secret` (shown only this one time), and use it as the Authorization header on every later call: create_proof, list_proofs, revoke_proof, get_balance, buy_stamps (verify_proof needs no auth). The key owns its own creator id, with no identity attached. Free stamps: one per network, so check `freeStamp` in the result; when it is false, the key needs prepaid stamps (buy_stamps) or x402 payment before its first stamp. Rate-limited to 3 keys per network per day; for 3 free stamps a month or a human-owned account, direct a person to makemark.io/account instead.

Stamp content with a permanent provenance record. Pass the sha256 hash of the content (hash it locally; the content itself is never uploaded). Returns an instant signed receipt: attach its verifyUrl, byline, badgeEmbed, and qrUrl to the published artifact. The receipt's `publisher` field carries the account's verified identity (domain/handle) or null. If you have no key, call create_account, store its one-time secret, and retry this same call with `Authorization: Bearer <secret>` (its `freeStamp` says whether a free stamp comes with it). If the response is `payment_required` or `quota_exhausted`, call buy_stamps and give a person the returned checkout link (prepaid packs never expire: 5 for $1.00, 10 for $1.50, 50 for $5.00, 100 for $8.00, 500 for $35.00, 1,000 for $65.00, 2,000 for $120.00), poll get_balance until the stamps arrive, then retry. To pay per stamp instead, sign one advertised x402 requirement and send it as a `PAYMENT-SIGNATURE` HTTP header: tool arguments can't carry it, so either configure your MCP client to send that header or POST the same JSON to https://makemark.io/proof directly. An `invalid_api_key` error means the key is mistyped or revoked: create a new one. The optional disclosure fields (aiDisclosure, usageNote, location) only show on `visibility: public` stamps and are unsigned metadata, not part of the cryptographic proof. The stamp asserts provenance from a signer at a time, not authorship truth.

Your key's stamp balance (requires API key): plan, included monthly stamps used and remaining, prepaid stamps (`balance`), whether a free stamp is still unused (`lifetimeSampleAvailable`), and recent pack purchases. Poll this after a person pays a buy_stamps link; credits usually arrive within seconds.

Grant a specific identity the ability to decrypt escrowed content. Only available for proofs created with content escrow opted in (not yet available — stamps are hash-only today). Returns a capability token the grantee uses with reveal.

List your recent stamps (requires API key).

Retrieve escrowed content for a proof you have been granted access to. Only available for proofs created with content escrow opted in (not yet available — stamps are hash-only today). The service re-checks H(content) == stampedHash before returning.

Revoke a stamp you created (forward-only: anchored history stays verifiable, but the proof is marked revoked from now on). Requires API key.

Verify content against all existing stamps. Pass a sha256 hash; matching is EXACT-BYTES-ONLY. Read the verdict fields: `exact` (these bytes are stamped), each proof's `publisher` (the verified identity: domain/handle + tier, or null meaning an unverified account, never trust a name that isn't in `publisher`), and `conflict` (2+ distinct signers claimed the same bytes; earliest anchored is listed first). A no-match on a re-encoded/screenshotted copy is EXPECTED and is not evidence of fakery: fetch the original and verify that. Free, no auth required.