Cloudflare

Articles

• Cloudflare 521 and firewall blocks

  Troubleshooting guide

  Fix Cloudflare 521 and related errors caused by origin firewalls. Allowlist the Cloudflare IP ranges, test, and avoid common blocklist mistakes.

• Cloudflare 521 origin refused connection

  Troubleshooting guide

  Diagnose and fix Cloudflare 521 origin refused connection. Check web server runs, port 443, firewall rules, IP binding and Cloudflare blocklists.

• Cloudflare 522 origin connection timed out

  Troubleshooting guide

  Diagnose and fix Cloudflare 522 origin connection timed out errors. Covers firewall blocks, DNS only testing, SSL mode misconfiguration, and 521, 524 and 525 variants.

• Cloudflare 522 vs 523 origin unreachable

  Reference guide

  Compare Cloudflare 522 and 523 origin errors. 522 is a timeout, 523 is unreachable. Fix DNS, routing, and firewall causes for each.

• Cloudflare 524 timeout explained

  Troubleshooting guide

  Understand Cloudflare 524 origin timeout, how the 100 second free plan limit behaves, and how to fix slow origin responses and long running work.

• Cloudflare 525 SSL handshake failed

  Troubleshooting guide

  Diagnose and fix Cloudflare 525 SSL handshake failed errors. Check SSL mode, origin TLS, certificate hostname and expiry, plus openssl connection tests.

• Cloudflare Argo Smart Routing explained

  Reference guide

  Cloudflare Argo Smart Routing: how it finds faster paths, Smart Shield bundling, costs and limits, and when to enable it.

• Authenticated Origin Pulls on Cloudflare

  Tutorial

  Set up Cloudflare Authenticated Origin Pulls so only Cloudflare can reach the origin and reject direct connections.

• Browser Cache TTL vs Edge Cache TTL in Cloudflare

  Reference guide

  Set Cloudflare Browser Cache TTL independently of the edge TTL, understand the 4 hour default and when Cloudflare overrides Cache-Control, and purge properly.

• Cloudflare cache TTL tuning with Cache-Control

  Reference guide

  Tune Cloudflare edge cache TTL: Cache-Control directives, s-maxage vs max-age, default TTLs, and Cache Rules to set caching duration.

• How to purge Cloudflare cache

  Tutorial

  Purge Cloudflare cache by URL, prefix or hostname, use the API, and understand that purging invalidates and re-fetches rather than deletes.

• Cloudflare Cache Reserve (HTML caching)

  Reference guide

  How to make Cloudflare cache your HTML: the default gap, a Cache Rule to the rescue, and where Cache Reserve extends persistence with its TTL and eligibility rules.

• Purge Cloudflare cache by cache tags

  Tutorial

  Purge Cloudflare cache by tags: add Cache-Tag headers at the origin, then issue one purge call that clears every asset carrying that tag.

• Cloudflare Crawler Hints and IndexNow

  Tutorial

  Use Cloudflare Crawler Hints plus IndexNow to notify search engines when content changes, based on cache hit or miss signals, available on all plans.

• Custom 5xx error pages on Cloudflare

  Tutorial

  Replace the default Cloudflare 5xx error pages with your own using Error Pages, custom error rules, and the diagnostic error tokens.

• Cloudflare DNS records explained

  Reference guide

  How Cloudflare DNS records work, the record types you will see, proxy mode versus DNS only, and steps to add or change a record safely.

• Cloudflare Email Routing for a custom domain

  Tutorial

  Set up Cloudflare Email Routing to forward custom-domain email to your existing inbox, and what forwarding-only means.

• Cloudflare Image Resizing for the edge

  Tutorial

  Resize and reformat images at the Cloudflare edge with Image Resizing. URL params, format, fit, and the transformation pricing model.

• Cloudflare Load Balancing origin pools explained

  Reference guide

  Cloudflare Load Balancing origin pools: how pools and monitors work, health thresholds, steering policies and failover behaviour.

• Lock down your Cloudflare origin IP

  Troubleshooting guide

  Lock your origin to Cloudflare IP ranges so a leaked IP cannot be hit directly. Includes firewall rules, CF-Connecting-IP trust, and automated list refresh.

• Cloudflare WAF managed rulesets explained

  Reference guide

  Cloudflare WAF managed rulesets: Cloudflare vs OWASP Core, score model, paranoia levels, plan availability, deployment and tuning.

• Preparing nameservers for Cloudflare

  Tutorial

  Prepare nameservers before moving a domain to Cloudflare. Export DNS records, lower TTL, verify delegation, and cut over without downtime.

• Cloudflare proxy mode (orange cloud) explained

  Reference guide

  What the Cloudflare orange cloud means on records. Compare proxied vs DNS only, and how the edge changes routing, caching, SSL and security.

• Cloudflare cache rules for dynamic content

  Reference guide

  Cloudflare cache rules for WordPress and dynamic sites. Cache rules vs page rules, bypass vs cache everything, and cookie behaviour explained.

• Cloudflare Page Rules vs Cache Rules

  Reference guide

  Cloudflare Page Rules vs Cache Rules: what Page Rules did, how Cloudflare replaced them, and which rule product handles each edge job.

• Cloudflare rate limiting basics

  Tutorial

  Set up Cloudflare rate limiting to protect login pages and APIs. Compare rate limit rules with HTTP 429, plus rule examples and limits.

• Getting the real visitor IP behind Cloudflare

  Tutorial

  Restore the real visitor IP at your origin with CF-Connecting-IP, use the web server's trusted proxy module, and prevent spoofing.

• Redirect rules on Cloudflare

  Reference guide

  Cloudflare redirect rules: Single and Bulk Redirects, dynamic wildcard rules, plan limits and when a redirect should stay at the origin.

• Cloudflare Security Level explained

  Troubleshooting guide

  How Cloudflare Security Level works, the default Medium setting, the retired threat score, when to use I'm Under Attack, and how to scope it with a configuration rule.

• Cloudflare SSL modes explained

  Reference guide

  Cloudflare SSL modes Flexible, Full, Full strict and Off explained. How each mode connects to the origin, and how to pick the right one.

• Cloudflare Transform Rules for headers

  Reference guide

  Use Cloudflare Transform Rules to set, add, or remove request and response headers at the edge without code. Free plan quota and Worker comparison included.

• Cloudflare Tunnel for local development

  Tutorial

  Use Cloudflare Tunnel (cloudflared) to share a local dev server over the internet. Learn quick tunnels for testing and named tunnels for stable hostnames.

• Cloudflare Turnstile setup guide

  Tutorial

  Install Cloudflare Turnstile on a website form. Learn the widget markup, the siteverify server-side check, and how it compares to a traditional CAPTCHA.

• Cloudflare Universal SSL versus a custom certificate

  Reference guide

  Cloudflare Universal SSL versus custom certificate: who issues each, coverage limits, and when to switch for your origin and brand.

• Cloudflare WAF custom rules

  Tutorial

  Write Cloudflare WAF custom rules with expressions and actions. Free/Pro/Business rule quotas, regex support and block vs challenge.

• Cloudflare Waiting Room basics

  Tutorial

  Set up Cloudflare Waiting Room to queue excess traffic during launches. How total_active_users, new users per minute and session duration work.

• Cloudflare Web Analytics basics

  Tutorial

  Add Cloudflare Web Analytics with a JS beacon or the proxy. What the free privacy-first metrics cover and how it compares to Google Analytics.

• Cloudflare Workers basics

  Reference guide

  Cloudflare Workers basics: serverless code at the edge, free plan limits, common use cases, and when a Worker is overkill.

• Workers fetch subrequests and their limits

  Reference guide

  Cloudflare Workers subrequest limits: what counts as a subrequest, Free 50, Paid 10,000, raising it in wrangler, and how redirect chains add to the total.

• Cloudflare Workers KV basics

  Reference guide

  Set up Cloudflare Workers KV. Learn the read/write limits, value size, cacheTTL, and when KV fits better than D1 for a Worker.

• Build a redirect rule with Cloudflare Workers

  Tutorial

  How to redirect legacy paths with a Cloudflare Worker: a small fetch handler, the pattern for prefix and regex redirects, and when a Single Redirect beats it.

• Cloudflare Workers storage KV vs R2 vs D1

  Reference guide

  Compare Cloudflare Workers KV, R2 and D1 for a Worker. Learn which store fits key-value, object and relational data, and how consistency shapes the choice.

• Cloudflare zone settings reference

  Reference guide

  Cloudflare zone settings: Brotli, 0-RTT, HTTP/2 to origin, IP Geolocation, Security Level and more, with defaults and plan availability.

• Cache keys for image CDN signed URLs

  Troubleshooting guide

  Signed image URLs add per-request signatures that break CDN caching. Customize the cache key to exclude X-Amz-Signature and related parameters.