By default, Shopify uses Google's reCAPTCHA v3 to help prevent spam through customer, contact, and blog comment forms.

reCAPTCHA v3 analyzes website visitor behavior to provide a score indicating the likelihood of the visitor being a bot. If the score is low enough, or too many requests are made within a short period of time, then Shopify falls back to reCAPTCHA v2 and the visitor is redirected to the /challenge page to complete the "I'm not a robot" challenge.

Merchants are able to disable reCAPTCHA functionality on the Online Store > Preferences page in the Shopify admin.