Metadata

Crossmint's minting infrastructure can validate and upload metadata to decentralized storage on your behalf. If you want to upload it yourself, simply pass the url to the API.

Collection and NFT metadata (e.g. title, description, image) must be specified in JSON format and follow industry conventions to ensure it renders appropriately across wallets and marketplaces.

Crossmint supports rich metadata like audio, video, and HTML. To include it, populate animation_url as specified in the links below.

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File-size Limits

Crossmint's standard plan has a 10mb file size limit. For larger uploads, you must upgrade to a premium plan or handle the upload yourself.

Metadata standards differ slightly across blockchains:

EVM chains

EVM chains follow the OpenSea standard. Refer to their official documentation to see what attributes can be included and how. Note that name and image are mandatory fields.

{
  "description": "This is the NFT description", 
  "external_url": "https://www.crossmint.com/", 
  "image": "https://www.crossmint.com/assets/crossmint/logo.png", 
  "name": "Crossmint Logo NFT",
  "attributes": [
    {
      "trait_type": "Flavor", 
      "value": "Minty"
    }
  ]
}

Solana

Solana follows the Metaplex Metadata Standard. For more information, refer to the official Metaplex documentation (look at the JSON structure section).

Example:

"metadata": {
  "name": "TEST NFT",
  "symbol": "TESTS",
  "description": "This is a test NFT",
  "seller_fee_basis_points": 5000,
  "image": "https://www.arweave.net/I5Hh_7aHWH21giaelic-Tah1p3kwA71fFur4yw5Bcls?ext=png",
  "attributes": [
    {
      "trait_type": "sun_size",
      "value": "l"
    },
    {
      "trait_type": "sun_pos",
      "value": "center"
    },
    {
      "trait_type": "random_seed",
      "value": 61
    }
  ],
  "properties": {
    "files": [
      {
        "uri": "https://www.arweave.net/I5Hh_7aHWH21giaelic-Tah1p3kwA71fFur4yw5Bcls?ext=png",
        "type": "image/png"
      }
    ],
    "category": "image"
  }
}