Infura

https://infura.io/ to create a custom Arbitrum RPC endpoint

Creating a New Account

Infura.io home page

Navigate to https://infura.io/ and create an account. This is a standard account creation.

When logging in for the first time a prompt to create a project will appear. This is the same dialog as the next step, Create New Project.

Create New Project

infura.io dashboard

Once account creation is complete the Infura dashboard can now be accessed. We need an HTTP link to create a custom network in MetaMask. To do this, click 'CREATE NEW PROJECT' as shown above.

"create new project" prompt

Select Ethereum under 'PRODUCT'. Give a name to your project then click 'CREATE'.

Infura dashboard with created project

Click 'SETTINGS' on the newly created project from the Infura dashboard.

"Endpoints" under General settings for infura project

In the General settings tab under keys there will be a drop down box for 'ENDPOINTS' Arbitrum Mainnet is not an option by default and has to be added to your newly created Infura project. Click the 'Add-on' link next to Arbitrum Mainnet from the 'ENDPOINTS' drop down box. This will bring you to the Manage Plan page for your Infura account.

Adding Arbitrum Rollup to Infura Plan(free)

Select the 'Arbitrum Rollup' check box.

Infura requires a card on file to add an Arbitrum Mainnet endpoint. 100,000 total requests are allowed daily on a free account. Click the 'GET STARTED NOW' box after entering your card info.

Arbitrum Mainnet Endpoint selected

You will now have access to an HTTP link for Arbitrum Mainnet. This is the link required to create a custom network. Copy and jump to Add Custom Network to MetaMask to complete setup.