--- title: "Fast linearized PDF downloads | Nutrient" canonical_url: "https://www.nutrient.io/guides/web/viewer/linearized-downloads/" md_url: "https://www.nutrient.io/guides/web/viewer/linearized-downloads.md" last_updated: "2026-06-08T09:14:14.485Z" description: "Boost PDF access speed with linearized downloading and improve user experience in web applications. Try it for free today!" --- # Enhance PDF viewing with linearized downloading Linearized PDFs allow viewing a PDF while it’s still downloading, enabling faster access to information in the PDF. This is especially useful for large documents where quick access is critical. For background on the format, see our [linearized PDF blog post](https://www.nutrient.io/blog/linearized-pdf.md). Document Engine with [streaming](https://www.nutrient.io/guides/document-engine/viewer/streaming.md) offers even more advantages, but sometimes linearized downloading is the best option. ## Comparison | | Document Engine streaming | Linearized downloading | | ------------------------------------- | ------------------------------------------------------------------------------- | ------------------------------------------------------------------------------- | | Fast initial page rendering | | | | Only requires HTTPS server | | | | Read-write while downloading | | | | Only downloads the required data | | | | Any PDF supported without preparation | | | ## Enable linearized downloading PDFs are read-only until fully downloaded. This means that while you can see the information in a PDF, you cannot, for example, add an annotation until the PDF is fully downloaded. 1. **Prepare your PDF for linearization**: This can be done using Nutrient’s [Document Engine](https://www.nutrient.io/guides/document-engine/optimization/linearize.md) or [.NET SDK](https://www.nutrient.io/guides/dotnet/optimization/linearize.md). If you’re using other third-party tools, PDF linearization might be called fast web loading. 2. **Upload the linearized PDF** to your HTTPS server. 3. **Load the document in `NutrientViewer.load`**. [`allowLinearizedLoading`](https://www.nutrient.io/api/web/interfaces/Configuration.html#allowlinearizedloading) is enabled by default, so no extra configuration is required: ```js NutrientViewer.load({ container: "#container", document: "https://example.com/path/to/linearized.pdf", }); ``` If you need to disable linearized downloading, set `allowLinearizedLoading: false`. If you use [dynamic font loading](https://www.nutrient.io/guides/web/viewer/fonts/dynamic-fonts.md) together with [font substitution](https://www.nutrient.io/guides/web/viewer/fonts/substitution.md), both continue to work while a linearized PDF is progressively loading. This helps avoid font-related fallbacks during the initial render of partially downloaded documents. ## Check server support Use curl to check if your server accepts range requests: ```bash curl -I https://example.com/path/to/linearized.pdf -H "Range: bytes=0-1" ``` If the server supports range requests, you’ll see a `206 Partial Content` response and an `Accept-Ranges: bytes` header. The HEAD request above may fail on some servers depending on how they handle requests. For example, S3 presigned URLs are HTTP verb-specific, so a URL signed for GET requests will reject HEAD requests. If the HEAD request fails, try using a GET request instead: ```bash curl -r 0-1 https://example.com/path/to/linearized.pdf -o /dev/null -w "%{http_code}\n" ``` This sends a GET request with a `Range` header. A `206` response indicates the server supports range requests. You might notice that very small linearized PDFs are downloaded in a single request, even when your server is correctly configured for range requests and responds with a `206 Partial Content` status. This is expected behavior and is due to a performance optimization in the viewer. - The viewer is designed to request a minimum initial block of data (a “chunk”) of approximately ~128 KB. This size is optimized to render the first page of most documents quickly. - If your PDF file is smaller than this ~128 KB threshold, the viewer’s initial request will cover the entire file, resulting in a single download. ## Additional information - This is strictly a feature to speed up viewing a PDF while downloading. It won’t allow you to modify the PDF until it’s fully downloaded. - Linearized downloading only has an effect when a PDF is downloaded from an external web server. - When using Nutrient Web SDK in the browser, temporary download storage is also managed automatically. For larger eligible PDFs, it may use the browser’s [origin private file system (OPFS)](https://developer.mozilla.org/en-US/docs/Web/API/File_System_API/Origin_private_file_system) to reduce peak browser RAM usage while the document downloads. If you want to disable that behavior, set [`tempStorage: "memory"`](https://www.nutrient.io/api/web/interfaces/Configuration.html#tempstorage). For more information, refer to the [temporary storage](https://www.nutrient.io/guides/web/open-a-document/temp-storage.md) guide. --- ## Related pages - [Client authentication and session renewal](/guides/web/viewer/client-authentication.md) - [Embed Web SDK in a dashboard/app shell](/guides/web/viewer/embed-in-dashboard-app-shell.md) - [JavaScript image viewer library](/guides/web/viewer/images.md) - [Create custom annotation toggle button](/guides/web/viewer/custom-annotation-toggle.md) - [JavaScript PDF viewer library](/guides/web/viewer.md) - [Page layout and scroll options in our JavaScript PDF viewer](/guides/web/customizing-the-interface/document-presentation-options.md) - [Office document viewing in JavaScript](/guides/web/viewer/office-documents.md) - [JavaScript PDF viewer library](/guides/web/viewer/pdf.md) - [Mobile responsive JavaScript PDF viewer](/guides/web/viewer/mobile-responsive.md) - [JavaScript Support in our PDF viewer](/guides/web/features/javascript.md) - [Enable or disable permissions in our JavaScript viewer](/guides/web/features/document-permissions.md) - [Production runtime setup checklist](/guides/web/viewer/production-runtime-setup-checklist.md) - [PDF document streaming in JavaScript](/guides/web/viewer/streaming.md) - [Zoom options in our JavaScript PDF viewer](/guides/web/viewer/zooming.md) - [macOS/Linux](/guides/web/viewer/troubleshooting.md)