Shopify Function

Functions replaced Shopify Scripts, which stopped executing on 30 June 2026 after the Script Editor went read-only on 15 April. A Function runs inside Shopify’s platform in under 5 milliseconds with no cold start, because it is compiled WebAssembly rather than code executed in a separately provisioned runtime.

The constraint that shapes every design decision is that a Function has no network access while it runs. It cannot fetch its own configuration during checkout, so whatever it needs has to already be inside Shopify when it executes - in practice, written to a metafield ahead of time and read from there. A single fetch target exists, but it is restricted to custom apps on Plus and Enterprise stores and requires Shopify’s approval, so any app that installs across plans has to assume no network at all.

Plan availability differs from Scripts in the way that matters. Scripts were Plus-only. A public App Store app containing Functions installs on any Shopify plan, and its discount or delivery logic works normally. Plus is only required to install a custom app that calls Function APIs directly - a Function your own team writes for a single store.

The full comparison, including what a Script looks like rebuilt as a Function and where Functions are still worse, is in Shopify Functions vs Scripts.