---
title: "Add a blockchain address as an NFT minter to an NFT smart contract"
method: POST
path: "/v3/nft/mint/add"
tags: ["NFT (ERC-721 or compatible)"]
---

# Add a blockchain address as an NFT minter to an NFT smart contract

`POST /v3/nft/mint/add`

## Request

- Base URL: `https://api.tatum.io`
- URL: `https://api.tatum.io/v3/nft/mint/add`
- Auth: API key in header `x-api-key`

/v3/nft/mint/add

**2 credits per API call**

Allow a blockchain address (the `minter` parameter in the request body) to mint NFTs on your NFT smart contract (the `contractAddress` parameter in the request body).

**NOTE:** Use this API **only** when you are using NFT Express with your own smart contract. For more information, see "Use your own smart contract to mint NFTs" in [Mint an NFT](#operation/NftMintErc721).  
Do not use this API in any other case.

This API is supported for the following blockchains:

*   BNB Smart Chain
*   Celo
*   Ethereum
*   Harmony
*   Klaytn
*   KuCoin Community Chain
*   Polygon
*   Flare
*   Cronos
*   Base
*   Avalanche
*   Fantom
*   Optimism

**Signing a transaction**  
When allowing a blockchain address to mint NFTs, you are charged a fee for the transaction, and you must sign the transaction with the private key of the blockchain address from which the fee will be deducted.

Providing the private key in the API is not a secure way of signing transactions, because the private key can be stolen or exposed. Your private keys should never leave your security perimeter. You should use the private keys only for testing a solution you are building on the **testnet** of a blockchain.

For signing transactions on the **mainnet**, we strongly recommend that you use the Tatum [Key Management System (KMS)](https://github.com/tatumio/tatum-kms) and provide the signature ID instead of the private key in the API. Alternatively, you can use the [Tatum JavaScript client](https://github.com/tatumio/tatum-js/tree/v2).

## Query parameters

- `testnetType` 'ethereum-sepolia' | 'flare-coston' | 'flare-coston2' | 'flare-songbird': Specifies the testnet type. The default is ethereum-sepolia for Ethereum (ETH) currency and flare-coston for Flare (FLR) currency. Valid testnet types depend on the specified currency.

## Headers

- `x-testnet-type` Schema (unresolved $ref)

## Request body

- union
  - AddNftMinter
    - `chain` 'BSC' | 'CELO' | 'ETH' | 'KLAY' | 'KCS' | 'MATIC' | 'ONE' | 'FLR' | 'CRO' | 'BASE' | 'AVAX' | 'OPTIMISM' | 'FTM', required: The blockchain to work with
    - `contractAddress` string, required: The blockchain address of the NFT smart contract
    - `minter` string, required: The blockchain address to add to the smart contract as an NFT minter<br/>To find the address of the Tatum NFT minter for your blockchain, see the table in "Use your own smart contract to mint NFTs" in <a href="#operation/NftMintErc721">Mint an NFT</a>.<br/>This address will cover your NFT minting fees. The number of credits equivalent to the fees will be then deducted from the credit allowance of your paid pricing plan.
    - `fromPrivateKey` string, required: The private key of the blockchain address that has priviledges to add an NFT minter to the NFT smart contract (the owner of the smart contract or a blockchain address that was granted such priviledges)
    - `nonce` number: The nonce to be set to the transaction; if not present, the last known nonce will be used
    - `fee` CustomFee: The custom defined fee; if not present, will be calculated automatically
      - `gasPrice` string, required: The price for one gas unit (in Gwei)
      - `gasLimit` string, required: The maximum number of gas units that you are willing to spend on processing the transaction at the provided gas price
    - `feeCurrency` 'CELO' | 'CUSD' | 'CEUR': (Celo only) The currency in which the transaction fee will be paid
  - AddNftMinterKMS
    - `chain` 'BSC' | 'CELO' | 'ETH' | 'KLAY' | 'KCS' | 'MATIC' | 'ONE', required: The blockchain to work with
    - `contractAddress` string, required: The blockchain address of the NFT smart contract
    - `minter` string, required: The blockchain address to add to the smart contract as an NFT minter<br/>To find the address of the Tatum NFT minter for your blockchain, see the table in "Use your own smart contract to mint NFTs" in <a href="#operation/NftMintErc721">Mint an NFT</a>.<br/>This address will cover your NFT minting fees. The number of credits equivalent to the fees will be then deducted from the credit allowance of your paid pricing plan.
    - `signatureId` string, uuid, required: The KMS identifier of the private key of the blockchain address that has priviledges to add an NFT minter to the NFT smart contract (the owner of the smart contract or a blockchain address that was granted such priviledges)
    - `index` number: (Only if the signature ID is mnemonic-based) The index of the address that holds the NFT smart contract that was generated from the mnemonic
    - `nonce` number: The nonce to be set to the transaction; if not present, the last known nonce will be used
    - `fee` CustomFee: The custom defined fee; if not present, will be calculated automatically
      - `gasPrice` string, required: The price for one gas unit (in Gwei)
      - `gasLimit` string, required: The maximum number of gas units that you are willing to spend on processing the transaction at the provided gas price
    - `feeCurrency` 'CELO' | 'CUSD' | 'CEUR': (Celo only) The currency in which the transaction fee will be paid

## Response `200`

OK

- union
  - TransactionHash
    - `txId` string, required: The hash (ID) of the transaction
  - SignatureId
    - `signatureId` string, uuid, required: The internal Tatum ID of the prepared transaction for Key Management Sysytem (KMS) to sign<br/>This is different from the <code>signatureId</code> parameter that you provided in the request body. The <code>signatureId</code> parameter in the request body specifies the signature ID associated with the private key in KMS.

## Other responses

- `400`: Bad Request
- `401`: Unauthorized. Not valid or inactive subscription key present in the HTTP Header.
- `403`: Forbidden. The request is authenticated, but it is not possible to perform the operation due to logical error or invalid permissions.
- `500`: Internal server error. There was an error on the server during the processing of the request.

---

[API](https://skmtc.dev/tatum/apis/smart-contracts.md) - [All operations](https://skmtc.dev/tatum/apis/smart-contracts/llms.txt) - [OpenAPI document](https://skmtc.dev/tatum/apis/smart-contracts/revisions/c0146043bb37?raw)