The __cf_bm cookie is a functional cookie necessary to support Cloudflare Bot Management, currently in private beta. As part of our bot management service, this cookie helps manage incoming traffic that matches criteria associated with bots.
Cloudflare places the__cf_bm cookie on the computers of end users visiting websites protected by Cloudflare and that use Cloudflare Bot Management to help protect their sites. It allows the Cloudflare-protected website to identify and not challenge the Internet user again while the cookie is present. This cookie is valid for a period of up to 30 minutes from the last request to the website.
Cloudflare customers can turn off the __cf_bm cookie at their discretion by disabling Cloudflare Bot Management. We encourage customers choosing to enable Cloudflare Bot Management (and hence, the __cf_bm cookie) to inform their end users about the existence of this cookie.
The __cf_bm cookie is an encrypted file containing Cloudflare’s proprietary bot score.