Third-party engines
Finally, it is important to realize that some antivirus software companies use third-party engines produced by other companies.
Here's a full list of vendors and the third-party engines they use (https://www.av-comparatives.org/list-of-consumer-av-vendors-pc/):
Understanding which antiviruses share third-party engines means that when you are gathering leads for one antivirus software, you can shorten your research time and use the same leads for another antivirus software.