ONLYOFFICE Desktop Editors is the feature-rich office suite, that allows you to open, create and edit documents, presentations and spreadsheets in different tabs of the same window, compatible with Microsoft Office and OpenDocument file formats, among others. It also offers you the option to add comments to your document to facilitate the communication. To collaborate and share files, you can connect it to an ONLYOFFICE portal that requires the creation of an account and comes with a 30-day trial period for teams. It allows you to create a single workspace for all your documents providing the desktop access to your Google Drive, DropBox, OneDrive, ownCloud accounts, etc. The support is provided via Forum.
Please note: the program includes a 1-year license and allows commercial use.