You can pick free open access journals without author processing charging/fee (APC) from Directory of Open Access Journals (https://www.doaj.org) website.
First, limit your search to JOURNALS (left-side form), type your desired field in Search form and click the SEARCH orange button on the right-end of the form. The next page will loads a list of journals related to your query. Find and click WITHOUT ARTICLE PROCESSING CHARGES (APCs), and the page will reload and provide a list of free open access journals without author processing charging/fee (APC) related to your query.
Hopefully this helps.