Glossary · Testing · also Shopify Functions
What is a Shopify Function?
A Shopify Function is a small program an app deploys to Shopify to customise part of Shopify’s backend logic, such as discounts, delivery options, payment options, or cart and checkout validation. Shopify runs it on its own infrastructure, compiled to WebAssembly, each time that logic executes, so the store’s theme and checkout code are left untouched.
- Reviewed 6 October 2026
In more detail
Functions are Shopify’s replacement for older ways of changing checkout behaviour, such as Shopify Scripts. Each Function receives a defined input, such as the cart, and returns a decision, such as which discount applies or which delivery option to hide.
Because Functions run inside Shopify’s own checkout, they work wherever that checkout runs, and they are held to strict limits on execution and size, which stops a misbehaving Function from slowing checkout down.
Stores on any plan can use public App Store apps that contain Functions; custom apps that contain Functions need Shopify Plus.
Key points
- Customises discounts, delivery, payment and validation logic.
- Runs on Shopify’s infrastructure as WebAssembly, within strict limits.
- Touches no theme file and no checkout code.
How Liftable relates
Sources
- Shopify docs: Shopify Functions. Describes Functions, the APIs they cover, the WebAssembly runtime and its limits, and plan availability: public apps with Functions on any plan, custom apps with Functions on Shopify Plus.
Related terms
Guides that go deeper
Last reviewed against the product on 6 October 2026.
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