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 (or MariaDB) database using the MySQLi and MySQLnd PHP components. A separate Sphider edition will work using PDO (PHP Data Objects) components in lieu of MySQLi and MySQLnd. 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. With a bit of work, you can port the PDO edition to either SQLite or PostgreSQL.
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.