Shopify Functions
Server-side code running in Shopify's infrastructure to customize backend commerce logic.
Server-side code running in Shopify's infrastructure to customize backend commerce logic.
Why It Matters
Functions let you customize core commerce logic that was previously locked: discount rules, shipping calculations, payment method visibility, cart validation. They run in Shopify's infrastructure (not your server), ensuring millisecond performance at checkout—where speed directly impacts conversion. Functions are the future of Shopify customization.
Practical Example
Scenario
A supplements brand wants to offer 'Buy 2, Get 1 Free' but only on specific product combinations and only for logged-in customers.
Calculation
A discount Function evaluates cart contents, checks customer authentication, and applies the discount if conditions are met—all in <5ms.Result
Complex promotional logic runs natively in checkout without app redirects or performance penalties. The promotion increases bundle purchases by 35%.
Pro Tips
- 1Start with Shopify's Function templates—they cover common use cases and handle boilerplate
- 2Use Rust or JavaScript/TypeScript—both compile to WebAssembly that runs in Shopify's infrastructure
- 3Test Functions thoroughly with edge cases—checkout is critical path, errors cost sales
- 4Monitor Function execution time—slow Functions can timeout and cause checkout failures