If the user is seeking alternatives because they need software but cannot afford the commercial license, the safest alternatives are legal ones.
Serials.ws became popular due to its simplicity. It required no downloading of executable files (reducing the immediate risk of viruses compared to downloading "cracked" EXEs) and operated in a legal grey area that was often slower to be targeted by litigators than torrent trackers. However, the era of the "simple serial" has effectively ended, necessitating a look at what alternatives exist today. Serials.ws Alternative