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In-depth guides
Longer walkthroughs for specific setups: real screenshots, code you can paste and the reason behind every step. The short fix page for each check lives under Learn.
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385 guides, page 4 of 33.
- SEO13 min read
403 forbidden: every cause and its fix
A 403 forbidden error means the server received the request and refuses to serve the page. What visitors can try, and every owner-side cause with its fix.Updated 10 Oct 2026 - Best practices14 min read
What is a reverse proxy? Caddy, nginx and Cloudflare explained
A reverse proxy is a server that sits in front of your website or app: it receives every request from the internet and forwards each one to the application behind it. What it is used for, the minimal Caddy and nginx configs, and the headers that keep it from breaking your site.Updated 9 Oct 2026 - Best practices12 min read
DNS_PROBE_FINISHED_NXDOMAIN: fixes for visitors and site owners
DNS_PROBE_FINISHED_NXDOMAIN means the DNS lookup came back with "no such name", so the browser had no address to connect to. Here are the visitor fixes in order, then how site owners find the expired domain or missing record behind it.Updated 8 Oct 2026 - SEO13 min read
502 bad gateway: what it means and how to fix it
A 502 bad gateway error means a proxy in front of the website asked the server behind it for the page and got no valid answer. The quick fix for visitors, then the owner's diagnosis, log lines and commands.Updated 7 Oct 2026 - SEO12 min read
AI visibility: what it is and how to measure it
AI visibility is how often AI assistants read your site, cite it in answers and send you visitors. Most of it is measurable with data you already have.Updated 5 Oct 2026 - Security12 min read
"Your connection is not private": what it means and how to fix it
"Your connection is not private" means the browser rejected the site's certificate: it has expired, covers another name, or comes from an issuer the browser does not trust. Here is the visitor fix, then the site-owner fix for each error code.Updated 4 Oct 2026 - SEO21 min read
301 redirects: what they are, when to use them and how they affect SEO
A 301 redirect tells browsers and search engines that a page has moved for good and sends them to the new address. What it does, when to use it and how to keep your rankings.Updated 4 Oct 2026 - SEO14 min read
301 vs 302 redirect: which to use, and when 307 or 308 fit
Use a 301 redirect when a page has moved for good and a 302 when the old address will come back. What each code tells browsers and Google, where 307 and 308 fit, and which one your server sends by default.Updated 4 Oct 2026 - SEO13 min read
500 Internal Server Error: causes and fixes for site owners
A 500 Internal Server Error means the server hit a problem it could not handle while building the page. What visitors can do, and how site owners find the cause and fix it.Updated 4 Oct 2026 - Security11 min read
Access-Control-Allow-Origin: what CORS allows and when * is dangerous
Access-Control-Allow-Origin tells browsers which other sites may read a response. What CORS is, when the * wildcard is fine, when it leaks data, and how to write a safe allowlist.Updated 4 Oct 2026 - Best practices13 min read
Brotli compression: gzip vs Brotli and how to enable it
Brotli compression shrinks HTML, CSS and JavaScript by around 80 % before they leave your server, a few percent better than gzip. What to compress, which to pick, and configs for nginx, Apache, Caddy and Cloudflare.Updated 4 Oct 2026 - Best practices13 min read
Browser caching: what to cache, for how long, and how to set Cache-Control
Browser caching lets returning visitors load your CSS, scripts, fonts and images from their own device instead of downloading them again. Three Cache-Control policies cover every file, with configs for nginx, Apache, Caddy, Cloudflare and WordPress.Updated 4 Oct 2026
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