There are open access publishers and journals which send unsolicited invitation to authors to submit an article for publication. Their main purpose is to be financially profitable, but they lack any real professionalism and do not meet scholarly standards. These journals are called predatory (or parasite) journals.
If you publish your article in a predatory journal you may not be able to publish it again in a serious scientific journal. Furthermore, it can harm your scientific reputation, so it is recommended to thoroughly examine the journal you wish to send your article to.
If there is any suspicion that you are dealing with a predatory journal, it is better to find another journal.
There are many signs that a journal is predatory, but it is always hard to conclusively decide because some of the criteria are true even in the case of real scientific open access journals. The main characteristics of the predatory journals are the following:

Contact:

  • they send unsolicited invitation to authors to submit an article for publication;
  • they usually only list an email address as a contact option;
  • their actual physical address is not declared;
  • the name of the publisher or journal is unknown.

Name of the journal, its mission, and discipline classification:

  • the articles are taken from several different disciplines;
  • the name of the journal is too generic and broad;
  • the articles published in the journal differ from that which the name implies.

Scholarly standards:

  • the editorial board is small, and members cannot be identified because no affiliation is listed;
  • there are no renowned researchers on the editorial board (or they are listed without their knowledge);
  • there are several typos, grammatical and translational errors on the website, commercial ads are featured;
  • the articles are published in a surprisingly short time because the review process is skipped.

Financing and legal issues:

  • the copyright of the article remains with the publisher;
  • they request a fee from the author upon submission;
  • they do not give adequate information about the publication fee.

Where can we check whether a journal is predatory or not?

Source/author of illustration: