> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstack.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Gnosis: Soulbound token with Remix and OpenZeppelin

> Create and deploy a non-transferable soulbound ERC-721 token on Gnosis Chain Chiado testnet using Remix, OpenZeppelin, and a Chainstack RPC node.

**TLDR:**

* Soulbound tokens are non-transferable ERC-721s, enforced via a transfer override, so they can only be minted or burned.
* This tutorial covers creating and deploying a soulbound token contract on the Gnosis Chain Chiado testnet through a Chainstack node.
* You’ll use Remix for development, MetaMask for signing, and Blockscout to verify and interact with the contract.
* Minting a token assigns it to an address, and that address alone can burn it, ensuring the token never changes ownership.

## Main article

Soulbound tokens, [originally proposed by Vitalik Buterin](https://vitalik.ca/general/2022/01/26/soulbound.html), at their core are simply non-transferable NFTs.

In this tutorial, you will:

* Create an ERC-721 contract that has a transfer override to make the token soulbound.
* Deploy the contract on the Gnosis Chain Chiado testnet through a node deployed with Chainstack.
* Interact with the deployed contract.

## Prerequisites

* [Chainstack account](https://console.chainstack.com/) to deploy a [reliable Gnosis Chain RPC endpoint](https://chainstack.com/build-better-with-gnosis-chain/).
* [Remix IDE](https://remix.ethereum.org/) to compile the contract and deploy through MetaMask.
* [MetaMask](https://metamask.io/) to deploy the contract through your Chainstack node and interact with the contract.

## Overview

To get from zero to a deployed soulbound token contract on the Gnosis Chain Chiado testnet, do the following:

1. With Chainstack, create a <Tooltip tip="A public chain project- a project to join public networks">public chain project</Tooltip>.
2. With Chainstack, join Gnosis Chain Chiado testnet.
3. With Chainstack, access your Gnosis Chain node credentials.
4. Set up your MetaMask to work through a Chainstack node.
5. With Remix IDE, create and compile the soulbound contract.
6. With Remix IDE, deploy the contract on the Gnosis Chain Chiado testnet.
7. Issue a soulbound token and burn it.

## Step-by-step

### Create a public chain project

See [Create a project](/docs/manage-your-project#create-a-project).

### Join the Gnosis Chiado testnet

See [Join a public network](/docs/manage-your-networks).

### Get your Gnosis Chain node access and credentials

See [View node access and credentials](/docs/manage-your-node#view-node-access-and-credentials).

### Set up MetaMask

See [Gnosis Chain tooling: MetaMask](/docs/gnosis-tooling#metamask).

### Create and compile the soulbound contract

1. Open [Remix IDE](https://remix.ethereum.org/).

2. On the home page, click **Environments** > **Solidity**.

3. On the left pane, click **File explorers** > **contracts** > **New File**.

4. In the modal, give any name to your contract. For example, `soulbound.sol`.

5. Put in the contract code:

   ```solidity theme={"system"}
   // SPDX-License-Identifier: MIT
   pragma solidity ^0.8.7;

   import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
   import "@openzeppelin/contracts/utils/Counters.sol";
   import "@openzeppelin/contracts/access/Ownable.sol";

   contract SoulBoundToken is ERC721, Ownable {
       using Counters for Counters.Counter;

       Counters.Counter private _tokenIdCounter;

       constructor() ERC721("SoulBoundToken", "SBT") {}

       function safeMint(address to) public onlyOwner {
           uint256 tokenId = _tokenIdCounter.current();
           _tokenIdCounter.increment();
           _safeMint(to, tokenId);
       }

       function burn(uint256 tokenId) external {
           require(ownerOf(tokenId) == msg.sender, "Only the owner of the token can burn it.");
           _burn(tokenId);
       }

       function _beforeTokenTransfer(address from, address to, uint256) pure override internal {
           require(from == address(0) || to == address(0), "This a Soulbound token. It cannot be transferred. It can only be burned by the token owner.");
       }

       function _burn(uint256 tokenId) internal override(ERC721) {
           super._burn(tokenId);
       }
   }
   ```

   This is your soulbound token contract:

   * It uses the audited OpenZeppelin libraries to make the contract of the ERC-721 standard, belonging to the deployer, and increments each issued token ID by 1.
   * The contract has a modification to prohibit the token transfer, which makes the issued tokens soulbound.
   * The contract also implements a burn function to allow the owner of the issued token to be able to burn it.

6. Compile the contract. On the left pane, click **Solidity compiler** > **Compile**.

### Fund your account

Fund the account that you will use to deploy the contract with xDAI. Use the [xDAI testnet faucet](https://gnosisfaucet.com/).

### Set up Remix IDE to work through your Chainstack node

On the left pane, click **Deploy** and switch to **Injected Provider - MetaMask**.

### Deploy the soulbound contract

On the left pane:

1. Click **Deploy & run transactions**.
2. In contract, select **contracts/soulbound.sol**.
3. Click **Deploy**.

This will engage your MetaMask to deploy the contract to the Gnosis Chain Chiado testnet through your currently selected MetaMask account. Click **Confirm** in the MetaMask modal.

### Interact with the contract

Once your contract is deployed, you can view it online at [Blockscout Gnosis Chain Chiado testnet explorer](https://blockscout.com/gnosis/chiado).

You are now going to verify the contract in the Blockscout explorer to be able to use the explorer as a web app and easily interact with the contract online.

### Flatten your contract code

Since your soulbound contract uses imported OpenZeppelin libraries, you must put all the imports into one `.sol` file to make Blockscout be able to verify it.

1. In your Remix IDE, click **Plugin manager** > **Flattener** > **Activate**.
2. Click **Flattener** > **Flatten contracts/soulbound.sol**.

The flattened contract is now in your clipboard.

### Verify the deployed contract on Blockscout explorer

1. Go to [Blockscout explorer](https://blockscout.com/gnosis/chiado).
2. Find your deployed contract. The address of your contract is on the left pane of Remix IDE under Deployed Contracts.
3. On the contract page on Blockscout, click **Code** > **Verify & Publish**.
4. Select **Via flattened source code**.
5. In **Contract Name**, provide the name of your contract. In our example, the name is `SoulBoundToken`.
6. In **Compiler**, select the same compiler version that was used in Remix IDE.
7. In **Optimization**, select **No**.
8. In **Enter the Solidity Contract Code**, paste the flattened contract code.
9. Click **Verify & publish**.
   Blockscout will take a few seconds to compile your contract, verify, and publish it.

### Issue a soulbound token

Now that your soulbound contract is verified, you can check Blockscout to interact with it.

1. On Blockscout, on your contract, click **Write Contract**.
2. In your MetaMask, make sure you have the same address selected as the one that deployed the contract.
3. Click **Connect wallet**. This will connect your MetaMask instance with the contract owner as the active address.
4. In **safeMint**, provide an address that you own and to which you will issue a soulbound token.
5. Click **Write**.

This will issue a soulbound token to the provided address.

### Burn the soulbound token

Now that your other account has a soulbound token, you can burn it.

In your MetaMask instance, switch to the account that has a soulbound token tied to it.

1. On Blockscout, on your contract, click **Write Contract**.
2. In your MetaMask, make sure you have the address selected that owns the issued soulbound token.
3. Click **Connect wallet**. This will connect your MetaMask instance with the token owner as the active address.
4. In **burn**, provide the token ID. If this is the first issued token, the ID is `0`.
5. Click **Write**.

This will send the soulbound token from the current owner to the address `0x0000000000000000000000000000000000000000`.

## Conclusion

This tutorial guided you through the basics of creating and deploying a simple soulbound contract on the Gnosis Chain Chiado testnet through your Chainstack-deployed node.

You have also interacted with the contract, issued, and burned the token using Blockscout as a web app and MetaMask as your interaction tool that works through your Chainstack-deployed Gnosis Chain node.

### About the author

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