Software testing workshops/certificates

Hi

Our team is lacking motivation and knowledge in testing our artifacts. Webapps, rest api’s, small services, ….

I want to get into that and need some kind of courses/workshops etc.

A coworker told me about ISTQB, which seems good.
Do you know some other institutions that provide good know how (international online only; in Germany with local attendance possible)? I would like to have a handful of options to compare them.

Thank you.