J2XML is an easy to use import/export extension for your Joomla! powered website. Use it to export articles, users and weblinks to an xml file and import those from this xml file in another website.
It can also be use to import data from an older Joomla version to a newer Joomla version like from Joomla 3 to Joomla 4. Although that version is still in beta at this moment (Jan 2023). You can also send articles, users and weblinks to another Joomla site. CLI (command line interface). It is also possible to export data from Wordpress to Joomla.