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The Assets API provides endpoints for querying native tokens and NFTs on the Cardano blockchain. You can retrieve asset information, locate NFTs, and check blacklisted policies.

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Available endpoints

Get asset info

Retrieve detailed asset information and metadata

Get NFT address

Find the current address holding a specific NFT

Get blacklist

Get list of blacklisted policy IDs

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Asset identifiers

Cardano native tokens are identified by two components:
ComponentDescriptionFormat
policy_idMinting policy hash56 hex characters
asset_nameToken name0-64 hex characters
The full asset identifier is: {policy_id}{asset_name} For example:
  • Policy ID: f0ff48bbb7bbe9d59a40f1ce90e9e9d0ff5002ec48f232b49ca0fb9a
  • Asset name: 4745524f (hex for “GERO”)
  • Full ID: f0ff48bbb7bbe9d59a40f1ce90e9e9d0ff5002ec48f232b49ca0fb9a4745524f

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Asset information

The asset info endpoint returns:
  • policy_id - Minting policy hash
  • asset_name - Token name (hex encoded)
  • asset_name_ascii - Token name (ASCII if printable)
  • fingerprint - CIP-14 asset fingerprint
  • quantity - Total supply
  • initial_mint_tx_hash - Transaction hash of first mint
  • mint_or_burn_count - Number of mint/burn events
  • onchain_metadata - CIP-25/CIP-68 metadata
  • metadata - Token registry metadata
{
  "policy_id": "f0ff48bbb7bbe9d59a40f1ce90e9e9d0ff5002ec48f232b49ca0fb9a",
  "asset_name": "4745524f",
  "asset_name_ascii": "GERO",
  "fingerprint": "asset1abc...",
  "quantity": "1000000000",
  "initial_mint_tx_hash": "abc123...",
  "mint_or_burn_count": 1,
  "onchain_metadata": {
    "name": "GERO Token",
    "image": "ipfs://Qm..."
  }
}

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NFT location

For non-fungible tokens (quantity = 1), you can find the current holder address using the NFT address endpoint. This is useful for:
  • Verifying NFT ownership
  • Tracking NFT transfers
  • Building NFT marketplaces

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Blacklisted assets

Some assets may be blacklisted due to:
  • Known scam tokens
  • Malicious smart contracts
  • Copyright violations
The blacklist endpoint returns an array of policy IDs that should be hidden or flagged in your application.

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Example: Get NFT holder

curl -X GET "https://nexus-dev.gerowallet.io/api/assets/nft-address?assetPolicy=f0ff48bbb7bbe9d59a40f1ce90e9e9d0ff5002ec48f232b49ca0fb9a&assetName=4745524f&network=MAINNET" \
  -H "Authorization: Bearer your-token"