A Flat File CMS is a CMS with no database. The data is structured around a matrix of folders and files without any import from a conventional database.
Is it reliable? That, of course, depends mostly on your project. A simple, clean and lean website will benefit from a flat file CMS in certain points of interest:
b. Harder to break, harder do crack – hacker’s work will be almost useless from site side breaches.
c. Speed – on a medium hosting solution, the average loading webpage time is below 30ms. Your website is no longer conditioned by database system and server. Running without extra weights has never felt better.
Of course, if you want to implement complex functions or features and you work with a large volume of data, the database CMS is the right choice for your needs.