{
  "version": "1.0",
  "schema": "https://entitymap.org/spec/v1.0",
  "publisher": {
    "name": "Gridcoin Blockchain Stamping",
    "url": "https://stamp.gridcoin.club"
  },
  "generated": "2026-07-20T00:00:00Z",
  "entities": [
    {
      "entityId": "stamping-service",
      "@type": "Service",
      "name": "Gridcoin Blockchain Stamping",
      "description": "A free Proof of Existence service that permanently certifies documents on the Gridcoin blockchain. Files never leave the browser — only their SHA-256 hash is stored on-chain.",
      "relations": [
        {
          "predicate": "ENABLES",
          "targetId": "proof-of-existence",
          "targetName": "Proof of Existence"
        },
        {
          "predicate": "DEPENDS_ON",
          "targetId": "gridcoin",
          "targetName": "Gridcoin"
        },
        {
          "predicate": "INCLUDES",
          "targetId": "stamping-api",
          "targetName": "Stamping API"
        },
        {
          "predicate": "RELATES_TO",
          "targetId": "gridcoin-stamp-action",
          "targetName": "Gridcoin Stamp GitHub Action"
        },
        {
          "predicate": "SUITED_FOR",
          "targetName": "Long-term document timestamping and proof of ownership",
          "confidence": "declared"
        }
      ],
      "hasChunks": [
        {
          "chunkId": "stamping-service-1",
          "text": "Gridcoin Blockchain Stamping is a free Proof of Existence service. Users drop a file in the browser, a SHA-256 hash is computed client-side, and the hash is embedded in a Gridcoin blockchain transaction using OP_RETURN. The file never uploads. Once confirmed, the proof is permanent and publicly verifiable.",
          "sourceUrl": "https://stamp.gridcoin.club/",
          "pageTitle": "Gridcoin Blockchain Stamping",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "definition"
        },
        {
          "chunkId": "stamping-service-2",
          "text": "Documents are never uploaded — only the SHA-256 hash is transmitted. No user accounts or personal data are collected, no tracking pixels are used, and the service is also available via a Tor onion service.",
          "sourceUrl": "https://stamp.gridcoin.club/about",
          "pageTitle": "Gridcoin Blockchain Stamping :: About",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "evidence"
        }
      ]
    },
    {
      "entityId": "proof-of-existence",
      "@type": "Concept",
      "name": "Proof of Existence",
      "description": "A technique that uses an immutable public blockchain to prove that a specific piece of data existed at a certain point in time. Once embedded and confirmed, the data cannot be altered or removed.",
      "relations": [
        {
          "predicate": "DEPENDS_ON",
          "targetId": "gridcoin",
          "targetName": "Gridcoin"
        },
        {
          "predicate": "REQUIRES",
          "targetId": "sha-256",
          "targetName": "SHA-256"
        },
        {
          "predicate": "SUITED_FOR",
          "targetName": "Proof of ownership, data timestamping, and data-integrity verification",
          "confidence": "declared"
        }
      ],
      "hasChunks": [
        {
          "chunkId": "proof-of-existence-1",
          "text": "Proof of Existence leverages blockchain technology to prove that a specific piece of data existed at a certain point in time. Because the blockchain is an immutable, decentralized public ledger, any data embedded in it cannot be altered or removed after confirmation.",
          "sourceUrl": "https://stamp.gridcoin.club/about",
          "pageTitle": "Gridcoin Blockchain Stamping :: About",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "definition"
        }
      ]
    },
    {
      "entityId": "sha-256",
      "@type": "Standard",
      "name": "SHA-256",
      "description": "A cryptographic hash function that maps a file of any size to a fixed 64-character hexadecimal digest. The stamping service computes this digest in the browser, so the file itself is never transmitted.",
      "sameAs": "https://en.wikipedia.org/wiki/SHA-2",
      "hasChunks": [
        {
          "chunkId": "sha-256-1",
          "text": "The file's SHA-256 hash is computed entirely client-side using js-sha256 — the file never leaves the user's device. Only the resulting hash is submitted to the stamping service.",
          "sourceUrl": "https://stamp.gridcoin.club/about",
          "pageTitle": "Gridcoin Blockchain Stamping :: About",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "evidence"
        }
      ]
    },
    {
      "entityId": "gridcoin",
      "@type": "Platform",
      "name": "Gridcoin",
      "description": "The decentralized blockchain network that stores stamp hashes. Each stamp transaction embeds the hash in an OP_RETURN output; once confirmed it is permanent and publicly verifiable.",
      "sameAs": "https://en.wikipedia.org/wiki/Gridcoin",
      "hasChunks": [
        {
          "chunkId": "gridcoin-1",
          "text": "The service embeds the hash in a Gridcoin blockchain transaction using an OP_RETURN script opcode. Once the transaction is confirmed on the blockchain, the proof is permanent and publicly verifiable.",
          "sourceUrl": "https://stamp.gridcoin.club/about",
          "pageTitle": "Gridcoin Blockchain Stamping :: About",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "evidence"
        }
      ]
    },
    {
      "entityId": "stamp-protocol",
      "@type": "Concept",
      "name": "Gridcoin Stamp Protocol",
      "description": "The on-chain data format for stamps. Each OP_RETURN payload carries a \"5ea1ed\" (\"Sealed\") identifier word, a protocol version, and up to two SHA-256 hashes.",
      "alternateName": "5ea1ed OP_RETURN stamp format",
      "relations": [
        {
          "predicate": "REQUIRES",
          "targetId": "sha-256",
          "targetName": "SHA-256"
        },
        {
          "predicate": "RELATES_TO",
          "targetId": "gridcoin",
          "targetName": "Gridcoin"
        }
      ],
      "hasChunks": [
        {
          "chunkId": "stamp-protocol-1",
          "text": "The hash is embedded using OP_RETURN. The payload begins with 6a46 (the OP_RETURN prefix) and the identifier word 5ea1ed (\"Sealed\"), followed by a protocol version and up to two 64-character SHA-256 hashes. Storing two hashes per transaction saves on fees.",
          "sourceUrl": "https://stamp.gridcoin.club/about",
          "pageTitle": "Gridcoin Blockchain Stamping :: About",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "procedure"
        }
      ]
    },
    {
      "entityId": "stamping-api",
      "@type": "Service",
      "name": "Stamping API",
      "description": "A public, unauthenticated, CORS-enabled JSON:API for creating stamps, looking up hashes, and querying the service wallet.",
      "relations": [
        {
          "predicate": "PART_OF",
          "targetId": "stamping-service",
          "targetName": "Gridcoin Blockchain Stamping"
        }
      ],
      "hasChunks": [
        {
          "chunkId": "stamping-api-1",
          "text": "The API is public, unauthenticated, and CORS-enabled, following the JSON:API specification. Endpoints let callers create stamps, fetch a stamp by id, look up the earliest stamp for a hash, and read the service wallet balance.",
          "sourceUrl": "https://stamp.gridcoin.club/developers",
          "pageTitle": "Gridcoin Blockchain Stamping :: API Reference",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "definition"
        }
      ]
    },
    {
      "entityId": "gridcoin-stamp-action",
      "@type": "SoftwareProduct",
      "name": "Gridcoin Stamp GitHub Action",
      "description": "A GitHub Action that anchors release assets to the Gridcoin blockchain on every published release, appending a verification table to the release notes.",
      "sameAs": "https://github.com/gridcat/gridcoin-stamp-action",
      "relations": [
        {
          "predicate": "DEPENDS_ON",
          "targetId": "stamping-api",
          "targetName": "Stamping API"
        },
        {
          "predicate": "RELATES_TO",
          "targetId": "stamping-service",
          "targetName": "Gridcoin Blockchain Stamping"
        }
      ],
      "hasChunks": [
        {
          "chunkId": "gridcoin-stamp-action-1",
          "text": "The Gridcoin Stamp Action anchors GitHub release assets to the Gridcoin blockchain on every \"release: published\" event. It computes the SHA-256 of every artifact on the runner, submits the hashes to the stamping API, and writes a \"Blockchain Timestamps\" table into the release body with a verification link per file.",
          "sourceUrl": "https://stamp.gridcoin.club/developers/github-action",
          "pageTitle": "Gridcoin Blockchain Stamping :: GitHub Action for CI/CD",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "procedure"
        }
      ]
    },
    {
      "entityId": "proof-certificate",
      "@type": "Service",
      "name": "Blockchain Proof Certificate",
      "description": "A public verification page and printable one-page PDF certificate for a confirmed stamp, carrying the hash, transaction id, block, UTC timestamp, and a QR code linking back to the proof.",
      "relations": [
        {
          "predicate": "PART_OF",
          "targetId": "stamping-service",
          "targetName": "Gridcoin Blockchain Stamping"
        }
      ],
      "hasChunks": [
        {
          "chunkId": "proof-certificate-1",
          "text": "Each confirmed stamp has a verification page at /proof/{hash} and a printable PDF certificate that includes the SHA-256 hash, transaction id, block, UTC timestamp, and a QR code, plus instructions for verifying the proof against any Gridcoin block explorer.",
          "sourceUrl": "https://stamp.gridcoin.club/llms-full.txt",
          "pageTitle": "Gridcoin Blockchain Stamping",
          "publisher": "Gridcoin Blockchain Stamping",
          "contentType": "evidence"
        }
      ]
    }
  ]
}