Metadata in the context of NFTs includes essential information such as the name, description, and media (e.g., images, videos) associated with the asset.

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Metadata Standards

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 rich metadata, simply populate animation_url as specified in the links below.

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 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.
EVM Metadata Example
{
  "name": "Crossmint Test NFT",
  "description": "Created with the Crossmint minting API",
  "image": "https://bafkreiexjl6kw4khdxkrt6dojgacscnzvrys47t472l2t7d6r2ss65kifq.ipfs.nftstorage.link/",
  "external_url": "https://docs.crossmint.com",
  "attributes":  [
    {
      "trait_type": "background",
      "value": "black"
    },
    {
      "trait_type": "flavor",
      "value": "minty"
    }
  ]
}

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Crossmint Metadata Storage

Metadata must be stored somewhere to be accessible and verifiable on the blockchain. Crossmint automatically uploads and validates metadata for you on decentralized storage solutions, ensuring a seamless minting experience.

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Supported Storage Providers

Crossmint supports two primary storage providers:
  • IPFS (InterPlanetary File System) (Default): A widely adopted decentralized storage standard ensuring compatibility across blockchain ecosystems by enabling peer-to-peer file storage and retrieval.
  • Walrus Network: A new decentralized storage solution designed for efficient and scalable metadata hosting. Walrus is currently not supported for EVM NFT templates.
If you are interested in using Arweave for metadata storage, please contact us for further information.

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Configuring Storage

By default, Crossmint uses IPFS to store metadata and media. However, if you prefer to use Walrus, you can configure this in the Crossmint Console under Settings > General. Storage Providers
If you prefer to upload and manage media files independently, you can pass a direct URL to the Mint API and set the reuploadLinkedFiles flag to false. This prevents Crossmint from automatically reuploading media files to decentralized storage.

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FAQs