You can create text OERs in the word processing application of your choice. LibreOffice (below) is a suite that includes a word processing application and a PDF editor
You can save your OER in any document format that doesn't require proprietary software to edit. PDFs are generally ideal for text OER.
You can also create a document in odt format (the open format version of .doc or .docx, which is proprietary to Microsoft) or create an HTML web page.
Open Source application that creates and edits PDFs and also is a vector drawing and graphics tool. A better option for PDF editing if your document is image-heavy.
A LibreOffice extension that enables optical character recognition to turn unreadable PDFs into readable ones. This makes them accessible, and is also important because it allows searching.
An Open Source office suite comparable to Microsoft Office. Document editing, spreadsheets, charts, presentations, small databases, images/PDFs, a mathematical formula editor, etc.
Create custom playlists of course readings and other material.
The Module Builder allows authors to create both student and instructor-facing content views. Authors are encouraged to include overviews, pedagogical supporting text, and instructions.
Allows faculty to create high-grade custom textbooks in both digital and print formats.
Open Textbook Network allows for modifying of their open textbooks using the Pressbooks platform.
A citation tool for open content.