Does plone work well with Cloudflare (Free)?

I have a site already https by Let's Encrypt

and the server front is setup with nginx + Varnish

now I am consider some attack protection thats why leaded to study of Cloudflare...

Anyone have experience of such setup? And what should I take care during the switch?

Thank you.

I have a few Plone sites behind Cloudflare. Works fine. As far as I know, cloudflare requires switching over your DNS to them. They provide HTTPS so you don't really need a separate certificate, but I think you can keep using your own certificate as well. Not sure if the free service supports that though.

Yes the free service works fine. I use it a lot.

Several Plone Foundation sites use CF. Plone.org, Plone.com, ploneconf.org, plonesymp.org

Are there not any 'restrictions', can the free version be used even for 'commercial' sites ?

No, and yes.