# SDK installation

**Note**: In SDK 4.x and above document auto-scanning and facial recognition are powered by WASM technology. The WASM module is available in three variants to accommodate different levels of browser capabilities:

* **uqudoScanModuleBasic**: Supports all the basic features
* **uqudoScanModuleAdvanced**: Includes SIMD support
* **uqudoScanModuleAdvancedWithThreads**: Incorporates both SIMD and threading support

To support and load fastest option, **uqudoScanModuleAdvancedWithThreads**, the web server hosting the page with the web SDK must include the following HTTP response headers:

* Cross-Origin-Embedder-Policy = "require-corp"
* Cross-Origin-Opener-Policy = "same-origin"

Please refer to <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Embedder-Policy> and <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Opener-Policy> to understand the implications of enabling these headers.