Or you can just link to a DB directly. A Flask app is just a WSGI app. You can mount and extend it with any kind of Python, no extension necessary.

That's what the extension does for you.

Can't session data be stored on disk? that's the default PHP behavior.

Because you might have multiple webservers.

There are solutions for that: Shared NAS, sticky sessions etc.

Good luck with maintaining that NAS. Your sticky sessions will logout all users on a server that goes down. It's better to have a db.

Please stop.

Of course it's better to have a db doh... I'm replying to your

> By default flask doesnt have a db.

People don't have NAS laying around. And don't use a filesystem as a db, especially a remote filesystem.