ahCrawler
A PHP search engine for your website and web analytics tool. GNU GPL3
... 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)