Shopify Checkout Extensions: How to Build Them in 2026 Custom Shopify checkout extensions help growing stores add approved fields, rules, tracking, and buyer-specific checkout experiences. This blog explains the development process for Shopify checkout extensions in 2026. It covers checkout UI extensions, Shopify functions, payment rules, delivery logic, validation, web pixels, and customer events. This guide includes examples for B2B buyers, regional customers, payment conditions, shipping choices, and custom data collection. Read our blog for more details. https://bit.ly/4cNumB7