An article processing fee (APF) is a fee charged by some open access journals to authors to cover the costs of publication, including peer review, editing, typesetting, and hosting the article on the journal's website. The fee is typically charged only if the article is accepted for publication after a rigorous peer review process.

The amount of the APF varies widely depending on the journal and the type of article. Some journals may charge a few hundred dollars, while others may charge several thousand dollars for more complex or lengthy articles. Some journals also offer discounts or waivers for authors from low-income countries, students, or members of the journal's sponsoring organization.

Critics of the article processing fee model argue that it creates a financial barrier to publication and may discourage authors from submitting their work to open access journals. However, proponents of the model argue that it is necessary to ensure the sustainability and quality of open access publishing, as traditional subscription-based publishing is no longer financially viable in the digital age. They also argue that the fees ensure that authors, rather than readers or libraries, bear the costs of publishing, which promotes greater transparency and accountability in scholarly communication.