Shopify Functions (Serverless Wasm Extensions)

Before writing code

Fetch live docs:

1. Fetch https://shopify.dev/docs/apps/build/functions for Functions overview
2. Web-search site:shopify.dev shopify functions input output for I/O schemas
3. Web-search site:shopify.dev shopify functions api reference for function types

What Are Shopify Functions

Serverless extensions that run on Shopify's infrastructure:

• Written in JavaScript or Rust
• Compiled to WebAssembly (Wasm)
• Execute within Shopify's checkout and backend pipeline
• 11 million instruction limit and 5ms execution time limit — must be extremely fast
• No network access, no filesystem — pure computation on provided input
• Wasm binary size limit: 256 KB, input JSON size limit: 64 KB