There are many different types of OA journals.
DOAJ is a community-curated online directory that indexes and provides access to high quality, open access, peer-reviewed journals. DOAJ is independent. DOAJ receives funding from institutions, libraries, publishers, aggregators, and research funders. All DOAJ services are free of charge including being indexed in DOAJ. All data is freely available. DOAJ operates an education and outreach program across the globe, focusing on improving the quality of applications submitted.
The DOAJ is both a directory and searchable database. The directory can be browsed by broad subject categories. Each journal title is assigned at least one broad subject category such as Technology and individual articles are assigned at least one subject category. Clicking on the subject category creates a list of all the journal titles assigned a given subject category and all of journal articles assigned the subject category. It also possible to search the DOAJ as a collection of articles.
SciELO (Scientific Electronic Library Online)
Digital library of OA journals mainly from 16 countries: Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Mexico, Paraguay, Peru, Portugal, South Africa, Spain, Uruguay, and Venezuela. The SciELO model exists to recognize, promote, and enhance high-quality journals published by universities, scientific societies, and professional associations. Most publications are Spanish, Portuguese, or English.