Draw.io is a free-to-use web application which can be fully used at absolutely zero cost. Users only have to pay for certain integrations, such as, JIRA, Conlfuence, etc. It's simple, easy-to-use interface lets you build meaningful diagrams in no time. Draw.io does not have any right on the content produced by users. They get 100% right on the content created and can use it for any purpose, be it personal or commercial. Diagrams can be either stored on Google Drive, Dropbox or locally on your system.