ahCrawler
A PHP search engine for your website and web analytics tool. GNU GPL3
...It consists of
* crawler (spider) and indexer
* search for your website(s)
* search statistics
* website analyzer (http header, short titles and keywords, linkchecker, ...)
You need to install it on your own server. So all crawled data stay in your environment.
You never know when an external webspider updated your content. Trigger a rescan whenever you want - you always have under control what data of what time were checked.
The spider is a CLI tool and must be added as a cronjob.
In a web based backend you can control all data and analyze your data.
You can handle multiple websites in the same backend.
PHP 7 or 8 + PDO (Mysql/ Sqlite)