Non-fungible token standard implementation for the Ethereum blockchain.

Usage no npm install needed!

<script type="module">
  import 0xcertEthereumErc721 from 'https://cdn.skypack.dev/@0xcert/ethereum-erc721';


THIS PACKAGE HAS MOVED TO @nibbstack/erc721.

ERC-721 Token — Reference Implementation

This is the complete reference implementation of the ERC-721 non-fungible token standard for the Ethereum and Wanchain blockchains. It is also compatible with other EVM compatible chains like Binance Smart Chain (BSC), Avalanche (AVAX) etc. This is an open-source project, complete with Hardhat testing.

The purpose of this implementation is to provide a good starting point for anyone who wants to use and develop non-fungible tokens on the Ethereum and Wanchain blockchains. Instead of re-implementing the ERC-721 yourself you can use this code which has gone through multiple audits and we hope it will be extensively used by the community in the future. Note that this implementation is more restrictive then the ERC-721 standard since it does not support payable function calls out of the box. You are however free to add this yourself.

If you are looking for a more feature-rich and advanced ERC721 implementation, then check out the 0xcert Framework.


All contracts and tests are in the src folder. There are multiple implementations and you can select between:

  • nf-token.sol: This is the base ERC-721 token implementation (with support for ERC-165).
  • nf-token-metadata.sol: This implements optional ERC-721 metadata features for the token contract. It implements a token name, a symbol and a distinct URI pointing to a publicly exposed ERC-721 JSON metadata file.
  • nf-token-enumerable.sol: This implements optional ERC-721 support for enumeration. It is useful if you want to know the total supply of tokens, to query a token by index, etc.

Other files in the tokens and utils directories named erc*.sol are interfaces and define the respective standards.

Mock contracts showing basic contract usage are available in the mocks folder.

There are also test mocks that can be seen here. These are specifically made to test different edge cases and behaviours and should NOT be used as a reference for implementation.


  • NodeJS 12+ is supported
  • Windows, Linux or macOS



This is the recommended installation method if you want to use this package in your JavaScript project.

This project is released as an npm module. You must install it using the npm command:

$ npm install @0xcert/ethereum-erc721@2.0.0


This is the recommended installation method if you want to improve the 0xcert/ethereum-erc721 project.

Clone this repository and install the required npm dependencies:

$ git clone git@github.com:0xcert/ethereum-erc721.git
$ cd ethereum-erc721
$ npm install

Make sure that everything has been set up correctly:

$ npm run test



To interact with this package's contracts within JavaScript code, you simply need to require this package's .json files:

const contract = require("@0xcert/ethereum-erc721/build/nf-token-enumerable.json");

Remix IDE (Ethereum only)

You can quickly deploy a contract with this library using Remix IDE. Here is one example.

You have created and have possession of unique glass-blown artwork (each having a serial/lot number) which you would like to sell using the Ethereum or Wanchain mainnet. You will sell non-fungible tokens and the buyers would be able to trade those to other people. One token per piece of artwork. You commit to anybody holding these tokens that they may redeem their token and take physical possession of the art.

To do this, simply paste the code below into Remix and deploy the smart contract. You will "mint" a token for each new piece of artwork you want to see. Then you will "burn" that token when you surrender physical possession of the piece.

pragma solidity ^0.8.0;

import "https://github.com/0xcert/ethereum-erc721/src/contracts/tokens/nf-token-metadata.sol";
import "https://github.com/0xcert/ethereum-erc721/src/contracts/ownership/ownable.sol";

 * @dev This is an example contract implementation of NFToken with metadata extension.
contract MyArtSale is

   * @dev Contract constructor. Sets metadata extension `name` and `symbol`.
    nftName = "Frank's Art Sale";
    nftSymbol = "FAS";

   * @dev Mints a new NFT.
   * @param _to The address that will own the minted NFT.
   * @param _tokenId of the NFT to be minted by the msg.sender.
   * @param _uri String representing RFC 3986 URI.
  function mint(
    address _to,
    uint256 _tokenId,
    string calldata _uri
    super._mint(_to, _tokenId);
    super._setTokenUri(_tokenId, _uri);


You should contact a lawyer before holding an auction, or selling anything. Specifically, laws for auctions vary wildly by jurisdiction. This application is provided only as an example of the technology and is not legal advice.


You can check the validity of the smart contract, the correctness of the implementation and the supported functions of the respective smart contract using the online validator at https://erc721validator.org/.


Ethereum - Ropsten testnet

We already deployed some contracts to the Ropsten network. You can play with them RIGHT NOW. No need to install the software. In this test version of the contract, anybody can mint or burn tokens, so don't use it for anything important.

Contract Token address Transaction hash
nf-token.sol 0xd8bbf8ceb445de814fb47547436b3cfeecadd4ec 0xaac94c9ce15f5e437bd452eb1847a1d03a923730824743e1f37b471db0f16f0c
nf-token-metadata.sol 0x5c007a1d8051dfda60b3692008b9e10731b67fde 0x1e702503aff40ea44aa4d77801464fd90a018b7b9bad670500a6e2b3cc281d3f
nf-token-enumerable.sol 0x130dc43898eb2a52c9d11043a581ce4414487ed0 0x8df4c9b73d43c2b255a4038eec960ca12dae9ba62709894f0d85dc90d3938280

Wanchain - testnet

We already deployed some contracts to testnet network. You can play with them RIGHT NOW. No need to install software. In this test version of the contract, anybody can mint or burn tokens, so don't use it for anything important.

Contract Token address Transaction hash
nf-token.sol 0x6D0eb4304026116b2A7bff3f46E9D2f320df47D9 0x9ba7a172a50fc70433e29cfdc4fba51c37d84c8a6766686a9cfb975125196c3d
nf-token-metadata.sol 0xF0a3852BbFC67ba9936E661fE092C93804bf1c81 0x338ca779405d39c0e0f403b01679b22603c745828211b5b2ea319affbc3e181b
nf-token-enumerable.sol 0x539d2CcBDc3Fc5D709b9d0f77CaE6a82e2fec1F3 0x755886c9a9a53189550be162410b2ae2de6fc62f6791bf38599a078daf265580


See CONTRIBUTING.md for how to help out.

Bug bounty

You are somebody that reads the documentation of smart contracts and understands how the ERC-721 Token Reference Implementation works. So you have unique skills and your time is valuable. We will pay you for your contributions to this project in the form of bug reports.

If your project depends on ERC-721 or you want to help improve the assurance of this project then you can pledge a bounty. This means you will commit to paying researchers that demonstrate a problem. Contact us at bounty@0xcert.org if interested. Thank you.

Read the full bug bounty program.


See LICENSE for details.