supabase/apps/docs/content/guides/functions/wasm.mdx

---
id: 'function-wasm'
title: 'Using Wasm modules'
component: true
description: 'How to use WebAssembly in Edge Functions.'
subtitle: 'Use WebAssembly in Edge Functions.'
---

Edge Functions supports running [WebAssembly (Wasm)](https://developer.mozilla.org/en-US/docs/WebAssembly) modules. WebAssembly is useful if you want to optimize code that's slower to run in JavaScript or require low-level manipulation.

This allows you to:

- Optimize performance-critical code beyond JavaScript capabilities
- Port existing libraries from other languages (C, C++, Rust) to JavaScript
- Access low-level system operations not available in JavaScript

For example, libraries like [magick-wasm](/docs/guides/functions/examples/image-manipulation) port existing C libraries to WebAssembly for complex image processing.

---

## Writing a Wasm module

You can use different languages and SDKs to write Wasm modules. For this tutorial, we will write a basic Wasm module in Rust that adds two numbers.

<Admonition type="note">

Follow this [guide on writing Wasm modules in Rust](https://developer.mozilla.org/en-US/docs/WebAssembly/Rust_to_Wasm) to setup your dev environment.

</Admonition>
<StepHikeCompact>
  <StepHikeCompact.Step step={1} fullWidth>
    <StepHikeCompact.Details title="Create a new Edge Function" fullWidth>
      Create a new Edge Function called `wasm-add`
      
      ```bash
      supabase functions new wasm-add
      ```

      </StepHikeCompact.Details>
    </StepHikeCompact.Step>

    <StepHikeCompact.Step step={2} fullWidth>
    <StepHikeCompact.Details title="Create a new Cargo project" fullWidth>
      Create a new Cargo project for the Wasm module inside the function's directory:

      ```bash
      cd supabase/functions/wasm-add
      cargo new --lib add-wasm
      ```

      </StepHikeCompact.Details>
    </StepHikeCompact.Step>
    <StepHikeCompact.Step step={3} fullWidth>
      <StepHikeCompact.Details title="Add the Wasm module code" fullWidth>

      Add the following code to `add-wasm/src/lib.rs`.

      <$CodeSample
        path="edge-functions/supabase/functions/wasm-modules/add-wasm/src/lib.rs"
        lines={[[1, -1]]}
        meta="lib.rs"
        language="rust"
      />

      </StepHikeCompact.Details>
    </StepHikeCompact.Step>

    <StepHikeCompact.Step step={4} fullWidth>
      <StepHikeCompact.Details title="Update the Cargo.toml file" fullWidth>

      Update the `add-wasm/Cargo.toml` to include the `wasm-bindgen` dependency.

      <$CodeSample
        path="edge-functions/supabase/functions/wasm-modules/add-wasm/Cargo.toml"
        lines={[[1, -1]]}
        meta="Cargo.toml"
      />

      </StepHikeCompact.Details>
    </StepHikeCompact.Step>

    <StepHikeCompact.Step step={5} fullWidth>
      <StepHikeCompact.Details title="Build the Wasm module" fullWidth>

        Build the package by running:

        ```bash
        wasm-pack build --target deno
        ```

        This will produce a Wasm binary file inside `add-wasm/pkg` directory.


      </StepHikeCompact.Details>
    </StepHikeCompact.Step>

</StepHikeCompact>

---

## Calling the Wasm module from the Edge Function

Update your Edge Function to call the add function from the Wasm module:

<$CodeSample
path="edge-functions/supabase/functions/wasm-modules/index.ts"
lines={[[1, -1]]}
meta="index.ts"
/>

<Admonition type="note">

Supabase Edge Functions currently use Deno 1.46. From [Deno 2.1, importing Wasm modules](https://deno.com/blog/v2.1) will require even less boilerplate code.

</Admonition>

---

## Bundle and deploy

Before deploying, ensure the Wasm module is bundled with your function by defining it in `supabase/config.toml`:

<Admonition type="note">

- You will need update Supabase CLI to 2.7.0 or higher for the `static_files` support.
- Static files cannot be deployed using the `--use-api` API flag. You need to build them with [Docker on the CLI](/docs/guides/functions/quickstart#step-6-deploy-to-production).

</Admonition>

```toml
[functions.wasm-add]
static_files = [ "./functions/wasm-add/add-wasm/pkg/*"]
```

Deploy the function by running:

```bash
supabase functions deploy wasm-add
```