# Prerequisites
The Keyless Web SDK has three conditions that must be met in order for it to run, these conditions mainly revolve around module loading, bundling and security headers.
### Run as Module
The main Javascript entrypoint of the `@keyless/sdk-web` or `@keyless/sdk-web-components` module which is `index.js` must be loaded as a module.
{% tabs %}
{% tab title="Headless" %}
```html
Keyless Web SDK
```
{% endtab %}
{% tab title="Web Components" %}
```html
Keyless Web SDK Components
```
{% endtab %}
{% endtabs %}
### Web Assembly Bundling
When building web applications it's extremely common to use a bundler, make sure yours is capable of bundling `.wasm` files.
### Security Headers
{% hint style="info" %}
This requirement applies only when using multi-threading, read more on [multi-threading](https://docs.keyless.io/web-sdk/web-sdk-reference/multi-threading "mention")
{% endhint %}
The Web Assembly module requires two security headers to run, if these headers are unset or have unfit values you won't be able to use the Keyless Web SDK.
| Name | Value |
| ---------------------------- | ------------ |
| Cross-Origin-Embedder-Policy | require-corp |
| Cross-Origin-Opener-Policy | same-origin |
In case you are loading resources from an external domain, make sure to load those resources in crossorigin, please read [Cross-Origin-Embedder-Policy: Avoiding Blockage With CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Cross-Origin-Embedder-Policy#avoiding_coep_blockage_with_cors) for more details.