LibreOffice is a free suite of apps for creating text documents, spreadsheets, presentations, and more, which you can then save in MS Office formats
LibreOffice is compatible with a wide range of document formats such as Microsoft® Word (.doc, .docx), Excel (.xls, .xlsx), PowerPoint (.ppt, .pptx) and Publisher. But LibreOffice goes much further with its native support for a modern and open standard, the Open Document Format (ODF). With LibreOffice, you have maximum control over your data and content – and you can export your work in many different formats including PDF.
You can download and use LibreOffice for free, but bear in mind that it doesn't include technical support or other value-added services.
LibreOffice is available for Windows, Mac OS, Linux, Web.