Issue an ERC-20 token with Remix, OpenZeppelin and Metamask

In this step-by-step tutorial you will learn how to issue and play with your own ERC-20 token on Ethereum. This tutorial can be completed by people with no blockchain programming experience and novice programmers.

We will use Metamask and the online version of Remix IDE

By the end of this tutorial you will be able to deploy standard ERC-20 Tokens! Please get your code verified and audited by a 3rd party before releasing any token to the public.

Preparation

Download and Install MetaMask

Install on Chrome, Firefox or Brave Browser
Create a new account and save your 12 word mnemonic
Select a test network. The Ropsten Network should work fine.

Get Some Testnet Ether

Click "Buy" or "Deposit" on Metamask or go to the Metamask Faucet or Ropsten Faucet
Hit "Send Me Ether". It should not take long (10-20 seconds)
Double check Ether was received by hitting the MetaMask Icon

Use OpenZeppelin for your Smart Contract Implentation

Find Source Code for a Standard ERC-20 Smart Contract. You want a well tested open source implementation such as the official Open Zeppelin implementation.

Navigate to the [OpenZeppelin Smart Contract Repository] (https://github.com/OpenZeppelin/openzeppelin-contracts/tree/master/contracts). Find

OpenZeppelin contain the solidity code you need to deploy your token, as well as useful tools and interfaces for more complex contract implementations. Their Github and documentation is worth a reading id you want to dive deeper into contract concepts.

Build your Solidity Smart Contract in Remix

Launch Remix
Enable the "Solidity Compiler" and "Deploy & Run Transactions" Tabs. Find them using the plugin manager on the left.

Copy the .sol files you need into remix. To create a new .sol file, click the "+" button in the top left. Either copy the code directly from github, or clone the repository and open the local files. e.g.

// SPDX-License-Identifier MIT AND GPL-3.0-only
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract MyOwnableToken is ERC20, Ownable {
    constructor() ERC20("MyOwnableToken", "MOTK") {
        _mint(msg.sender, 1000 * 10 ** decimals());
    }

    function mint(address to, uint256 amount) public onlyOwner {
        _mint(to, amount);
    }
}

Remix will import all dependencies automatically and create metadata necessary for deployment.
Try compiling the contract by pressing ctrl-s or pressing the compile button on the compile tab.
Ensure the contract compiles correctly
Rename your base file to rename your token e.g. YourTokenName.sol

Customize your Smart Contract

Now you can personalize the token according to your preferences.

The guides in the OpenZeppelin docs site will teach about different concepts, and how to use the related contracts that OpenZeppelin Contracts provides:

Access Control: decide who can perform each of the actions on your system.
Tokens: create tradeable assets or collectives, and distribute them via Crowdsales.
Gas Station Network: let your users interact with your contracts without having to pay for gas themselves.
Utilities: generic useful tools, including non-overflowing math, signature verification, and trustless paying systems.

Compiling and Deploying

Check for errors on remix. Yellow warnings are ok. Red warnings must be fixed before the next step.
Make sure you are still on the Run tab
Select YourTokenName in the drop down menu
Select "Injected Web3" for your environment (Make sure MetaMask is logged in and running)
Click Deploy
Approve the transaction on metamask. You may need to enable pop ups on your browser
Wait for the transaction to mine! Check for confirmation on EtherScan. You can click on your latest transaction in metamask.
After the transaction has mined, click the contract address and copy it
Paste it into the Tokens sectionin Metamask

You have now issued your first Token. Great Work! This is just the tip of the iceberg.

Notes

Gas price should auto update. For live Eth use https://ethgasstation.info/

Optional - Register and Verify

Now we are going to register this contract. To do this:

Using Etherscan: In the Overview Tab → Click on the Contract Address
Go to the Contract Code Tab → Click Verify and Publish
Make sure to install Flattener plugin and flatten your code (so it includes all the imports)
On Etherscan select single file and MIT license

Words of Wisdom: Get it right once or get it wrong forever.

Be sure that the contract address field corresponds to the contract address that you have just deployed. Remember contract address is different to your public key
The contract name has to match the one in the code.
Enter the correct compiler version. At the time of writing, this is Compiler: 0.8.7+commit.e28d00a7 In future builds, this can be found by hitting the Details tab under Compile, and selecting the Compiler dropdown under MetaData.
On Optimisation, choose No.
On ENTER THE SOLIDITY CONTRACT CODE BELOW, copy the flattener output code from Remix, and paste in that area.
Leave the other fields in blank and click on Verify and Publish.

If you get a success! It worked.

To confirm that it worked, go to https://ropsten.etherscan.io/ and look up your metamask address. Hit the View Tokens dropdown to see if you tokens are in there.

Sending Tokens

Send some to your neighbours:

In Metamask Open the menu and click "Add Tokens"
Click Add Custom Token and Input your Contract Address. Your token details should appear automatically
You should now see your token balance. Try sending some tokens to your friend's address Check Etherscan for progress
Your friend can then enter your contract info and code to view your tokens in their wallet!

felipeclopes / ERC20-TokenTutorial-Remix