About the Cart and Checkout Validation Function API

The Validation API allows developers to provide their own validation of a cart and checkout, including express checkouts, such as PayPal, Shop Pay, Google Pay, and Apple Pay.

Example use cases

Anchor link to section titled "Example use cases"

Use tokengating or require a customer membership at checkout.
Verify the age or ID of a customer when they proceed through checkout.
Provide B2B product minimums, maximums, and multiples.
Provide B2B location order minimums, maximums, or credit limits.
Specify quantity limits in a flash sale.

Developer tools and resources

Anchor link to section titled "Developer tools and resources"

Shopify CLI

A command-line tool for building Shopify apps.

Validation API reference

Consult the GraphQL reference for the Validation API.

Limitations and considerations

Anchor link to section titled "Limitations and considerations"

The Validation API doesn't currently support draft orders.
Validation functions are cached. This can result in a delay (typically, less than one minute) between changes being made and those changes being live.
You can install a maximum of five validation functions on each store.

Next steps

Anchor link to section titled "Next steps"

Learn how to use Validation functions by validating a cart and checkout.