Cloudflare SSL/TLS modes: Flexible vs Full vs Full (strict)
# SSL/TLS encryption modes
The mode controls encryption between Cloudflare and your origin (visitor-to-Cloudflare is always encrypted on proxied records).
- **Off**: no encryption anywhere. Only for origins that genuinely cannot do TLS.
- **Flexible**: HTTPS between visitor and Cloudflare, plain HTTP to the origin. Easy to set up, dangerous in one specific way (see below).
- **Full**: HTTPS to the origin, but Cloudflare does not validate the origin certificate (self-signed works).
- **Full (strict)**: HTTPS to the origin with a valid, trusted certificate. Cloudflare strongly recommends Full or Full (strict).
## The Flexible trap
With Flexible, Cloudflare talks HTTP to your origin. If your origin redirects HTTP to HTTPS (as most do), Cloudflare follows the redirect... back to itself over HTTPS... then talks HTTP to the origin again. Infinite redirect loop. This is the single most common Cloudflare redirect-loop cause, and the fix is to move to Full or Full (strict), not to add more redirect rules.
## Automatic SSL/TLS
Newer zones may have Automatic SSL/TLS, which picks the most secure mode your origin supports and ramps up cautiously. It never downgrades you: if your origin cert expires on Full (strict), it stays on Full (strict) and starts failing rather than silently dropping to Full. Monitor your origin cert expiry regardless.
## Checklist
- Default to Full (strict) with a valid origin cert (Cloudflare Origin CA certs are free and trusted by Cloudflare).
- If you inherit Flexible, treat it as tech debt with a redirect-loop risk, not a stable state.
- After changing modes, clear cache: Flexible-to-Full transitions change cache keys and the ramp is deliberately slow.Find related guidance
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