ONLYOFFICE Desktop Editors is a free open source office suite that combines text, spreadsheet and presentation editors allowing to create, view and edit documents stored on your Windows/Linux PC or Mac without an Internet connection. It is fully compatible with Office Open XML formats: .docx, .xlsx, .pptx.
The ONLYOFFICE desktop suite pack allows extending the functionality with the pre-installed plugins, e.g. you can insert special symbols and ClipArts, edit pictures, translate text, send documents as mail attachments right from the editors, etc.
The suite also provides quick access to broad collaborative capabilities. Users are able to switch to the online mode by connecting to the cloud (ONLYOFFICE cloud, Nextcloud, ownCloud) and collaborate on documents with the team in real time.
Additional capability is end-to-end encryption that allows protecting documents (DOCX, XLSX, PPTX, ODT, ODS, ODP) with the AES-256 encryption algorithm. Currently available as a developer preview.