Open Access Journals are freely available to others, undergo a peer review process that is often compatible with traditional journals, and will often require an Article Processing Charge to cover publication costs.
Predatory publishers use the Open Access Journal model to profit by charging authors to publish in their journals, however many do not have a true peer review process. Publishing in these journals can be harmful to researchers who think they are publishing in reputable journals.
Beall's List of Potential Predatory Journals and Publishers can be used as a guide to identify potential predatory publishers or low-quality journals.
You can find trusted Open Access Journals through the non-profit organization called the Directory of Open Access Journals. You can also limit your search journals without article processing charges and that receive a DOAJ seal.