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What is Cloudflare, and what does it do for a website?

Cloudflare sits between visitors and your server as DNS, CDN, firewall and more. What each part does, the free plan, and the settings that often break sites.

Cloudflare is a network that sits between visitors and your website. It provides DNS, a CDN that caches and speeds up delivery, free HTTPS, DDoS protection, a firewall and bot management, plus developer platforms such as Workers and Pages. The free plan covers most small sites. Wrong SSL and firewall settings cause most problems.

Published · Last updated

By Michal Měřínský. Audit methodology.

How it works

You point your domain's name servers at Cloudflare. For each DNS record you choose proxied, the orange cloud, or DNS only, the grey cloud. Proxied traffic goes through Cloudflare's network, which can cache, compress, filter and secure it before it reaches your server. DNS-only records just resolve normally.

What it does

  • DNS hosting, fast and free.
  • CDN: caches static files near visitors and compresses responses.
  • HTTPS: a certificate at the edge, automatic HTTPS rewrites and HSTS settings.
  • Security: DDoS protection, a web application firewall, rate limiting and bot management.
  • Developer platform: Workers for code at the edge, Pages for static sites, R2 for object storage, and more.

The SSL mode setting

The SSL/TLS encryption mode decides how Cloudflare talks to your server:

  • Flexible: HTTPS to the visitor, plain HTTP to your server. If your server redirects HTTP to HTTPS, this causes an endless redirect loop.
  • Full: HTTPS to your server, without validating its certificate.
  • Full (strict): HTTPS to your server with a valid certificate. This is the setting to use.

Most Cloudflare-related outages on small sites are a Flexible SSL mode or a firewall rule that blocks real visitors or search engine crawlers.

Settings to check

  • SSL mode: Full (strict).
  • Always Use HTTPS: on, unless your origin already redirects.
  • Bot and firewall rules: confirm verified search engine crawlers are allowed. Bot protection that answers 403 to Googlebot removes pages from Google.
  • AI crawler settings: Cloudflare offers options to block AI crawlers. Decide deliberately, because blocking them can also keep you out of AI answers that cite sources.
  • Caching: do not cache pages that are personal to a logged-in user.
  • Page and redirect rules: avoid chains with redirects your server already does.

When it helps and when it does not

Cloudflare helps most when visitors are far from your server, when you face bot or attack traffic, or when your host does not provide HTTPS and caching. If your site is on Vercel, Netlify or Cloudflare Pages already, you have a CDN, and adding another proxy layer in front often complicates more than it helps.

What a scan can and cannot tell you

WebAuditOS sees what Cloudflare delivers: HSTS, HTTPS redirects, cache headers, compression and redirect chains. Cloudflare challenge pages that answer the scanner are recognized and not graded as page errors.

It cannot see your Cloudflare dashboard settings, firewall events or whether specific crawlers are blocked. Check the firewall event log and Search Console for that.

If a scan sees a bot challenge instead of your page, real search engine crawlers may be challenged too. Check your bot settings.

Short answers

Is Cloudflare free? The free plan covers DNS, CDN, HTTPS and basic protection for most small sites.

Is Cloudflare a host? It can host static sites with Pages and code with Workers. For most sites it sits in front of another host.

Why is my site in a redirect loop after adding Cloudflare? The SSL mode is probably Flexible. Use Full (strict).

Does Cloudflare help SEO? Faster delivery helps. Blocking crawlers by mistake hurts.

In the product

The checks this maps to

Every check named here runs on every scan, on every plan - what a plan changes is how many pages are crawled, how long the history is kept and what you can do with the result. These are the ids the findings carry, so you can match a line in a report to the explanation above.

Performance

What is a CDN, and does your website need one?

A CDN serves your site from servers close to each visitor. What it speeds up, what it does not, how caching works, and when a small site benefits from one.

HTTP errors

Why does my site say too many redirects, and how do you fix it?

ERR_TOO_MANY_REDIRECTS means pages redirect in a loop. The usual causes, including CDN SSL settings and conflicting www rules, and how to trace the chain.