An ODT file is a text document created by various word processors, such as the Writer program included in Apache OpenOffice and LibreOffice. It contains different elements such as text, images, drawn objects, and styles. ODT files are formatted using the OASIS OpenDocument XML-based standard.

ODT file open in Apache OpenOffice Writer 4.1.3 ODT files are commonly created and opened by the Writer word processor, which is one of several programs available in the OpenOffice and LibreOffice suites. It is similar to the Word program available in the Microsoft Office suite. The ODT file is the main file used by Writer to save documents the same way that Word saves documents in the .DOCX file. OpenDocument text files can be opened and edited with any OpenOffice-compatible program, including: NeoOffice (Mac), AbiWord (Mac & Windows), and KWord (Unix). They can also be imported into Google Docs, Google's web-based word processor included with Google Drive. ODT files can also be opened in Microsoft Word and saved as DOCX files. NOTE: Apache OpenOffice was formerly known as OpenOffice.org.

An ODT file is a theme file used by Origin, a data analysis and graphing application used by various scientists and engineers. It contains settings in XML format that customize the appearance of one or more dialog windows that appear in Origin.

ODT theme files are not meant to be opened by a user. Instead, the file stores settings that are referenced by Origin to make up the appearance of dialog windows in the software. NOTE: ODT files are typically located in the "Dialog" folder of the C:\Program Files\OriginLab\Origin<version>\Themes installation.