Is there a product that allows you to build a search engine that has hundreds of websites in it?

Hope you're doing great. Is there a product that allows you to build a search engine that has hundreds of websites. The Google Custom Search is Limited. "If your custom search engine includes more than 20 sites, the results may differ from the results of a 'site:' search on Google.com and your search engine may sometimes display fewer results." https://support.google.com/progr... I've yet to find a solution for this. Regards, Hashem