The Publisher [Frontiers][1] was - and, since there is no further development, still is - listed on Beall's List. Starting from scratch and with problems and therefore seen as predatory in the beginning by some researchers, Frontiers is now a reputable publisher with their journals listed in Scopus, Web of Science and the Journal Citation Report. The whole story is even included in their [Frontiers' Wikipedia article][2]. 


  [1]: https://www.frontiersin.org
  [2]: https://en.m.wikipedia.org/wiki/Frontiers_Media