# Overview Telerik Document Processing includes the **RadSpreadStreamProcessing** library for importing and exporting large spreadsheet files with a low memory footprint. Use the `SpreadExporter` and `SpreadImporter` APIs to process XLSX and CSV documents sequentially. The library has no dependency on Microsoft Excel, Microsoft Office, or third-party UI components. ![Telerik RadSpreadStreamProcessing overview diagram showing streaming spreadsheet processing between CSV input and XLSX output](https://www.telerik.com/document-processing-libraries/documentation/assets/028a01373724f652f7c0c71f674d176a/spread-stream-processing-overview.jpg) To skip this introductory article, see [how to get started with RadSpreadStreamProcessing](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/getting-started). > note If you do not yet have Telerik Document Processing installed, see [the first steps for installation](https://www.telerik.com/document-processing-libraries/documentation/getting-started/first-steps). ![Telerik RadSpreadStreamProcessing worksheet example showing an Orders Log report with filters, shipping values, discounts, and color-coded status cells](https://www.telerik.com/document-processing-libraries/documentation/assets/8f5e3ac2b5f1ba62f0adf0aacea662f7/spreadstreamprocessing-overview_01.png) > tip You can find the code sample from the previous image in the [Document Processing SDK repository on GitHub](https://github.com/telerik/document-processing-sdk/tree/master/SpreadStreamProcessing/GenerateDocument). ## What Is Spread Streaming Spread streaming is a document-processing approach that lets you create or read large spreadsheet documents with high performance and low memory use. The library saves memory by writing spreadsheet content directly to a stream instead of keeping a full workbook model in memory. Exporters write content as you create worksheets, rows, and cells, and finalize the file when you dispose them. During import, `RadSpreadStreamProcessing` parses only the required data chunk. This approach helps keep CPU and memory use low. ## Key Features The library supports the following features: * Generate large XLSX and CSV documents (1M+ rows). * Create documents from scratch, or append worksheets to existing workbooks. * [Export to XLSX and CSV files](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/export). * [Import from XLSX and CSV files](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/import). * Write directly to a stream, or read only the required data. * Use less memory than [RadSpreadProcessing](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadprocessing/overview) for large-file scenarios. * **Append** new worksheets to an existing workbook. * **Grouping**: Organize data in sections, and show or hide the relevant ranges. * Hidden [rows](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/model/row) and [columns](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/model/column): Set the hidden state of each row or column. * [AutoFilter](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/autofilter): Show or hide rows based on column values. `AutoFilter` supports value, custom comparison, top or bottom N, and dynamic date filters. * [Cell formatting](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/model/cells#set-a-format): Apply the required appearance to cells. * [Cell styles](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/cell-styles): Apply multiple format options in one step and keep formatting consistent. * [Merge cells](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/model/cells#merge-cells): Merge adjacent cells across multiple rows and columns. You can also control the view state of a sheet: * [Set the scale factor](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/worksheet-view-exporter#scale-a-document). * [Control the selection and active cell](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/worksheet-view-exporter#add-selection-to-a-document). * [Show or hide gridlines](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/worksheet-view-exporter#hide-grid-lines-and-row-or-column-headers). * [Show or hide row and column headers](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/worksheet-view-exporter#hide-grid-lines-and-row-or-column-headers). * [Freeze panes](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/worksheet-view-exporter#freeze-panes) to keep part of the worksheet visible while scrolling. * [Change the first visible cell](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/worksheet-view-exporter#change-the-first-visible-cell) to control the part of the sheet that appears when a viewer opens the document. ## RadSpreadStreamProcessing versus RadSpreadProcessing The main differences between the two spreadsheet processing libraries include: * `RadSpreadStreamProcessing` writes directly to a stream, while [RadSpreadProcessing](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadprocessing/overview) builds an in-memory document model. As a result, the streaming library uses much less memory. * **RadSpreadStreamProcessing** does not run formula or layout-related calculations, so file generation is faster than with **RadSpreadProcessing**. ## When to Use RadSpreadStreamProcessing Use the `RadSpreadStreamProcessing` library when you need to create or read large datasets with low memory use. You can also append data to an existing document stream. Export the generated document directly to a file or stream, for example, to send it to a client. ## Online Demos The following demos show common `RadSpreadStreamProcessing` scenarios: | Demo | Description | | ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------- | | [SpreadStreamProcessing Large Document Export](https://demos.telerik.com/document-processing/spreadstreamprocessing) | With the SpreadStreamProcessing APIs, you can generate large XLSX and CSV files. | | [SpreadStreamProcessing Import Document](https://demos.telerik.com/document-processing/spreadstreamprocessing/import_document) | This example shows how you can retrieve data from XLSX or CSV files using the SpreadStreamProcessing library. | ## See Also * [Getting Started](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/getting-started) * [Workbook](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/model/workbook) * [Worksheet View Exporter](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadstreamprocessing/features/worksheet-view-exporter) * [RadSpreadProcessing](https://www.telerik.com/document-processing-libraries/documentation/libraries/radspreadprocessing/overview)