Create a PHP script to check if files (PHP / HTML / ...) have not changed on servers (Ubuntu) or on the Internet.

- Check the specified files (path) on servers via sFTP. - Check if the content of the web address (URL) was not changed. - Database (MySQL). Store the information which files need to be checked and how they must be checked (URL / PATH); Server IP addresses and logins; URL / PATH addresses; What was changed; Etc. - The database have to be optimized to store only changes that were made (what and when it was changed, etc.). - Allow grouping of all URL / path in the database. - RSS feeds with the list if there were changes in files (RSS url hashed and assigned to each group individually). - Clicking on the RSS link has to open a new page (hashed URL) and display specific changes to the files visually (right/left-side comparison of a specific place / change). The text has to be allowed to be copied. - Files can be compared over a different period if changes were made. - Allow downloading the latest (live version) file (zip format) and associated (src) files (img, css, js, etc.) - Allow to download the latest (live version) file (to the server (sFTP)) and related (src) files (img, css, js, etc.). - API. Get a changelog; File download link (zip); Add new URL / path; Add new servers; Add groups (on return: get url hash). - API can have different APP KEY to get / manage different groups or master API key to get and manage all groups. One API key for one group, the other APY key for another group or one common API for all groups. - Develope without using frameworks (native PHP). - NO backend interface. Only interface to see file changes. - Unlimited Webhooks amount for all groups and each one separately. - Adjustable time for each group individually when to check file changes.