Shopify Functions Explained (With Examples)
What Shopify Functions are, when to use them, and how they replace fragile checkout-script apps on Plus.
Elena Vasquez
April 22, 2026 · 10 min
Why Functions exist
Functions let you customize discounts, shipping, and payment logic with server-side code that runs inside Shopify's checkout — replacing the checkout-script apps that Checkout Extensibility retired.
They're fast, versioned, and predictable, which makes them a far safer foundation than the app stack they replace.
A concrete example
A tiered wholesale discount that used to require a checkout-script app becomes a small, testable Function you own in your repo.
Because Functions run within Shopify's limits, you get consistent behavior without adding checkout latency.
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