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SEO guide · 10 categories · 240+ checks

The Kalenux SEO guideEvery check, explained.

Every check our audit runs, in plain English: what it is, why it affects your rankings, and exactly how to fix it. Organised by category so you can go straight to what’s hurting your site.

Last reviewed · 1 Oct 2026Reference library →Kalenux engineering
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how a search engine processes a page
01Crawlgate
02Indexgate
03Linksdiscovery
04Sitemapdiscovery
05Contentquality
06Speedquality
07Securitytrust
08Localetrust
↳ fail an early step and later ones don’t count
what an audit checks

240+ checks. A handful of categories.

Kalenux runs 240+ individual checks, but they fall into a handful of categories. Work through them in priority order: fix what stops a page from being crawled or indexed first, then optimise everything else.

SEO problems are easiest to solve when you understand why each one matters rather than chasing a list of red flags. This guide explains the reasoning behind every category, so a fix is something you understand instead of something you copy.

THE ORDER A SEARCH ENGINE ACTUALLY PROCESSES A PAGE
01→
CrawlIt has to reach the URL before anything else is possible.
02→
IndexThen decide whether the page is allowed into the index.
03→
DiscoverFollow links and a sitemap to find it and pass it authority.
04
RankOnly then: content, performance, security and localization.

Read the categories below in the order they’re listed and you’re reading them in the order that decides whether a page can rank at all.

browse by category

Start at the top. Crawl and index come first.

Crawlability and indexability are the foundation everything else sits on.

FOUNDATION01
CrawlabilityCan search engines even reach your pages? Covers robots.txt, crawl budget, and the directives that decide what gets discovered. If a page can’t be crawled, nothing else matters.Read the category →
FOUNDATION02
Indexability & canonicalsIs the page allowed into Google’s index, and which URL is the master copy? Covers noindex, canonical tags, and the canonical mistakes that quietly deindex whole sections.Read the category →
DISCOVERY03
Links & internal linkingBroken links, orphan pages, anchor text, and how authority flows through your site. The link graph decides which pages search engines treat as important.Read the category →
DISCOVERY04
RedirectsRedirect chains, loops, and 301 vs 302. Done wrong, redirects leak the link equity you spent years earning.Read the category →
DISCOVERY05
SitemapsYour XML sitemap is a direct instruction to crawlers. It should contain only canonical, indexable, 200-status URLs, and nothing else.Read the category →
QUALITY06
Content & metadataTitles, meta descriptions, headings, duplicate content and thin pages: the on-page signals that affect both ranking and click-through.Read the category →
QUALITY07
Performance & Core Web VitalsLCP, CLS and INP. Speed is a ranking factor and the first thing a user feels. Slow templates cost rankings and conversions at once.Read the category →
TRUST & REACH08
Localization & hreflangIf you serve multiple languages or regions, hreflang is the most error-prone area in SEO. Covers return tags, self-references and valid codes.Read the category →
TRUST & REACH09
Security & certificatesHTTPS is a confirmed ranking signal, and a lapsed certificate can take a domain offline for visitors. Covers TLS, mixed content and response headers.Read the category →
SUMMARY10
ChecklistsThe 20-point technical audit and the SEO mistakes that most often kill rankings: the highest-impact checks from every category in one list.Read the category →
how to use this guide

Three ways in, depending on what you know.

◎New to technical SEO?Start at Crawlability and read straight through in order. Each category builds on the one before it, which avoids optimising content on a page that can’t even be indexed yet.Start with Crawlability →
⌕Chasing a specific problem?If Search Console or an audit already told you what’s wrong, jump straight to the matching category: a stray noindex belongs in Indexability, a slow LCP in Performance, a broken return tag in Localization.Open the audit guide →
≡Just want the summary?Skip to Checklists for the 20-point technical audit and the 15 mistakes that recur most often across sites: the highest-impact items from every category in one ordered list.Go to Checklists →
the Kalenux reference library

Eleven articles, 185 primary sources.

Encyclopedia-style articles for readers, researchers and anyone who needs to cite a fact. Every claim links to Google’s documentation, an IETF standard or another primary source.

ARTICLELAST REVIEWED 1 OCT 2026 · CITE-READY
00Technical search engine optimizationStart here: what technical SEO is, Google’s Search Essentials, and how the areas fit together.19 sources→01Web crawling and crawlabilityHow search engines discover and download pages, and how robots.txt controls access.19 sources→02Search indexing, noindex and canonical URLsWhat decides whether a crawled page is stored and which duplicate is shown.17 sources→03Internal links and anchor textHow links drive discovery and relevance, from PageRank to rel="ugc".16 sources→04HTTP redirects and SEOEvery 3XX status code, how Google treats it, and how to migrate safely.13 sources→05XML sitemapsThe sitemaps.org protocol, its limits, and which tags Google actually reads.14 sources→06Titles, snippets and duplicate contentHow Google builds title links and snippets, and how it handles duplicates.18 sources→07Web performance and Core Web VitalsLCP, INP and CLS: thresholds, measurement, history and fixes.25 sources→08Hreflang and international SEOLanguage and region codes, reciprocal links, site structure and how Google detects language.15 sources→09HTTPS and website security for SEOHTTPS as a ranking signal, mixed content, HSTS, security headers and hacked sites.17 sources→10SEO audits and site migrationsPre-launch checks, Google’s migration procedure and ongoing monitoring.14 sources→10Site migrations and SEOMoving domains, protocols or URL structures without losing search visibility.12 sources→

Reading about it is step one.Running it is step two.

The audit finds which checks your site is failing, on which pages, and tracks them over time so you can see the fixes working. Free to start, no subscription.

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