Upload a Premiere Project (.prproj) file and this tool will instantly convert it to be openable in any older version of Premiere.
Your file will automatically download upon clicking Convert.
This tool is not yet able to convert Premiere 2021 or 2022 projects to earlier versions. I'm working on a fix to this but it's proving more complicated than I hoped.
A Premiere project (.prproj) file is basically an xml file wrapped up in gzip compression. One of the nodes contains a version number corresponding to the version of Premiere which created it. Premiere checks this when opening a file and refuses to open anything with a lower version number, even when the project is basically compatible: "This project was saved in a newer version of Adobe Premiere Pro and cannot be opened in this version."
This tool simply changes that version number to '1' and creates a gzip compressed file which Premiere can read. You can perform the same process yourself manually, as described here, however this tool makes it simple.
Because this is a cheat, some filters and effects may be lost when converting.