An OTW file is a workbook template created by Origin, a data analysis and graphing application used by various scientists and engineers. It contains the layout settings for one or more worksheets, which include the number of rows and columns, theme, and added notations. OTW files are used to create .OGW workbooks.

You can only open OTW files with Origin, which can be used to create, open, and edit OTW files. The program is only available for Windows. To open an OTW file in Origin, select File → Open..., select the "Origin Template .otw" file type, navigate to the OTW file location, and click Open. NOTE: The release of Origin 2018 included an updated unicode format for saving workbook templates (.OTWU), which features performance advantages over the older, non-unicode OTW file format.