This can be accomplished by using elements and campaign settings, as well as URL API.

The elements and campaign method:

• Make sure your campaign has Recurring giving set to Only one timeCreate a Simple Form Element and set the Default Amount to Customize, then select the desired amount. For this example, we have selected $1,000:

When you click the button, you will see the following:

The URL API method:

On your website or marketing materials, you can create a link that would include the following parameters:

• amount
• modifyAmount

Clicking this link would open up a checkout with a specific amount without the ability to change the amount.

For this example, we have used $100 as the amount:

Example: https://website.org/?form=FUNXXXX&amount=100&modifyAmount=no

This URL opens up the following checkout:

To read more about URL API, please see our related help center article:

Using URL API Parameters