The Project Management Institute requires people to complete 35 hours training before applying for Project Management Professional (PMP) certification.

Many third-party providers offer training courses for this purpose, both online and classroom-based. Some of them mention that they teach with Microsoft Project for the examples.

Does anybody know of training companies or web sites who provide a course recognized by PMI using free software like OpenProject instead of MS Project?

I tried two search engines and a search of the forum and couldn't find an answer.

If they use other software like Redmine or ProjectLibre that is also interesting for me.

Yes, i do know one PMP Training provider which is edureka. They may offer software like openproject instead of MS project. You can surely check out their course.