Remix IDE

Write, compile, and deploy Solidity contracts to Hedera testnet from your browser.

Remix is an open-source Solidity IDE that runs in the browser. It compiles, debugs, and deploys without anything installed locally. Because Hedera is EVM-compatible, the same Remix workflow you’d use against Ethereum works against Hedera once MetaMask is pointed at the JSON-RPC relay.

The rest of this page walks through that workflow end-to-end.

Prerequisites

MetaMask configured for Hedera Testnet

Network Hedera Testnet, RPC https://testnet.hashio.io/api, Chain ID 296.

Testnet HBAR

A small amount of testnet HBAR to pay for deployment.

Step 1: Open Remix

Go to remix.ethereum.org. Accept the default workspace if it asks. The left sidebar gives you a File Explorer, the Solidity Compiler, and the Deploy & Run Transactions panel.

Step 2: Write a contract

In File Explorer, create contracts/HelloHedera.sol and paste:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.22;

contract HelloHedera {
    string public message = "Hello, Hedera!";

    event MessageUpdated(address indexed by, string newMessage);

    function updateMessage(string memory newMessage) public {
        message = newMessage;
        emit MessageUpdated(msg.sender, newMessage);
    }
}

Step 3: Compile

1. Open the Solidity Compiler tab.
2. Set the compiler version to 0.8.22 (or anything that satisfies the pragma).
3. Click Compile HelloHedera.sol. Green checkmark means success.

Turn on Auto compile in the compiler settings so Remix recompiles every save. Saves a click on every edit.

Step 4: Connect MetaMask

1. Switch to the Deploy & Run Transactions tab.
2. In the Environment dropdown, pick Injected Provider - MetaMask.
3. MetaMask asks to connect. Approve.
4. The Network field should read Custom (296) network. That’s Hedera testnet.

If it shows a different network, switch MetaMask to Hedera Testnet from its own network dropdown.

Step 5: Deploy

1. Confirm the CONTRACT dropdown shows HelloHedera.
2. Click the orange Deploy button.
3. MetaMask prompts to confirm the transaction. Review the HBAR gas fee and click Confirm.
4. The contract appears under Deployed Contracts at the bottom of the panel after a few seconds.

Step 6: Interact with the contract

Expand the deployed contract under Deployed Contracts. You get a blue read-only message button that returns the current value at no gas cost, and an orange updateMessage field that writes a new value (this one costs gas).

Click message to see the initial value. Type something into updateMessage and call it. Confirm the MetaMask popup. Click message again to see the new value.

Step 7: View on HashScan

Copy the contract address from the Deployed Contracts panel and open:

https://hashscan.io/testnet/contract/<your-address>

HashScan shows the deploy transaction, the bytecode, and any subsequent calls. If you want the source code readable on HashScan, verify the contract with the same Solidity file you used in Remix.

When to reach for Remix

Use case	Tool
Quick prototyping, single contract	Remix
Reproducible deploys, tests, scripts	Hardhat or Foundry
Guided UI for ERC-20 / ERC-721 templates	Contract Builder
Cross-chain libraries (LayerZero, CCIP)	Hardhat. Remix’s import resolution gets shaky

Remix is the right tool when you’re learning, poking at one contract, or doing throwaway experiments. Once you want version control, a test suite, or repeatable CI deploys, move to Hardhat or Foundry.

See also

Contract Builder

Browser-based deploys without writing any Solidity yourself.

Hardhat

Move your Remix contract into a Hardhat project for tests and CI.