An OTT file is a document template saved in OASIS' OpenDocument standard format and created by word processors included in the OpenOffice and LibreOffice suites. It contains the page layout and default styles for a text document. OTT files are used for authoring .ODT documents that have the same appearance and formatting.

OTT file open in Apache OpenOffice Writer 4.1.3 OTT templates are used for saving documents that are repeatedly used but with minor edits applied to them for each use. Some examples of these types of documents include company letterheads, memo templates, newsletters, cover letters, business plans, or templates for other official document types. In Writer, which is the word processor included in the Apache OpenOffice suite, you can create your own templates with custom page layout, fonts, and styles. You can also download templates from the OpenOffice website by selecting File → New → Templates and Documents and then clicking "Get more templates online...".