a PHP spider and search engine
Sphider is a lightweight web spider and search engine written in PHP. It can be implemented using a MySQL, MariaDB, SQLite, or PostgreSQL database using PDO (PHP Data Objects). The MySQL and MariaDB options also work using the MySQLi and MySQLnd PHP components in lieu of PDO. PHP 7.x is supported. It is a great tool for adding search functionality to your web site or building your custom search engine. Sphider supports all standard search options, plus word autocompletion and spelling suggestions. Sphider is capable of indexing images while spidering content. RSS feeds may also be indexed.
If you run into problems, you can probably get an answer to your question in the forum.
A full list of Sphider features can be seen in the About section.
While hitting on a variety of topics, the WorldSpaceFlight Blog is home to many postings relating to the Sphider search engine.