Synology Office spreadsheet format for spreadsheets managed through Synology Drive
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OSHEET is a proprietary spreadsheet format associated with Synology Office and Synology Drive. It is used for spreadsheets stored and managed in a Synology Drive environment rather than as a broadly interchangeable desktop workbook format.
These files are generally opened through the Synology Drive web interface or Synology Office on a configured Synology NAS. Synology Drive Client may also associate with the format on Windows, although the spreadsheet is normally edited through the connected Synology service.
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Date updated: September 22, 2026
OSHEET files represent Synology Office spreadsheet documents. The format is controlled by Synology and may contain spreadsheet data, formulas, formatting, and document-management information intended for use within a Synology Office workspace.
Unlike common formats such as .xlsx and .ods, OSHEET is not a widely supported interchange format. Its MIME association is commonly identified as application/x-synology-drive-sheet, and local handling may involve the Synology Drive Client component cloud-drive-ui.exe.
Synology Office is designed for collaborative, browser-based work through Synology Drive and DSM. Consequently, compatibility depends on the Synology Office version, NAS configuration, and account permissions. There is no established native support for opening OSHEET documents directly in Microsoft Excel, LibreOffice, or Apple Numbers.
On Windows, Synology Drive Client can provide integration with the associated Synology service. On macOS and Linux, users typically access the document through a supported web browser connected to Synology Drive. A file received outside its original Synology environment may not open correctly without access to the relevant NAS or cloud workspace.
To open an OSHEET document, sign in to the Synology Drive web portal connected to the NAS where the document is stored, then open it with Synology Office. On Windows, installing and configuring Synology Drive Client may synchronize the document and provide its file association, but it does not make the format a standard standalone spreadsheet.
On macOS or Linux, use a current web browser to access Synology Drive and Synology Office. If the file was downloaded from another system, upload it back to the appropriate Synology Drive workspace or ask the owner to export it to a more widely supported format.
The most reliable way to convert an OSHEET document is to open it in Synology Office and use its export or download function, when available, to create an XLSX, ODS, or CSV file. The available formats can vary by Synology Office version and administrator settings.
There is no broadly established desktop or online converter that reliably supports the proprietary OSHEET format. Avoid uploading confidential spreadsheets to unverified online conversion services. After exporting, the resulting XLSX or ODS file can be edited with Microsoft Excel, LibreOffice, or compatible office software; converting back to OSHEET generally requires importing the spreadsheet into Synology Office rather than renaming the file.
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