Sessions in Flask can be considered "client-side", as sessions are stored client-side in browser cookies.
- Validating and creating sessions is fast (no data storage)
- Easy to scale (no need to replicate session data across web servers)
- Sensitive data cannot be stored in session data, as it’s stored on the web browser
- Session data is limited by the size of the cookie (usually 4 KB)
- Sessions cannot be immediately revoked by the Flask app
For more, review Sessions in Flask.