Arbitrum
Arbitrum is an Ethereum scaling solution that provides high throughput and low-cost smart contract execution.
Arbitrum is EVM-compatible. Developers can connect via Arbitrum's node API. The Arbitrum node is compatible with Ethereum's JSON-RPC API implementation, which allows using tools such as Infura, Hardhat, and MetaMask.
To use the Arbitrum blockchain, create a Web3 project and add the Arbitrum network add-on.
On off-chain protocols: sidechains and rollups
Read Infura blog for more information on off-chain protocols such as sidechains and rollups.
For more information on Arbitrum see Arbitrum's official documentation.