Flexible - SSL/TLS encryption modes
Setting your encryption mode to Flexible makes your site partially secure. Cloudflare allows HTTPS connections between your visitor and Cloudflare, but all connections between Cloudflare and your origin are made through HTTP. As a result, an SSL certificate is not required on your origin.
Use when
Choose this option when you cannot set up an SSL certificate on your origin or your origin does not support SSL/TLS.
Required setup
Depending on your origin configuration, you may have to adjust settings to avoid Mixed Content errors or redirect loops.
Limitations
Flexible mode is only supported for HTTPS connections on port 443 (default port). Other ports using HTTPS will fall back to Full mode.
If your application contains sensitive information (personalized data, user login), use Full or Full (Strict) modes instead.