Technical SEO covers the parts of search optimisation that have nothing to do with the words on a page — how easily search engines can crawl, understand, and index your site, and whether anything is quietly blocking that process. A website can have excellent content and still underperform badly if the underlying technical foundation is broken, since search engines simply can't properly evaluate content they can't access or understand. This checklist covers the 25 factors most worth checking, roughly in order of how often they turn out to be the actual problem.
Crawlability and indexing (items 1–6)
- Confirm your site isn't accidentally blocked in
robots.txt— a single misconfigured line can quietly deindex an entire site. - Check for a valid, submitted XML sitemap in Google Search Console, covering all pages you actually want indexed.
- Verify important pages return a proper 200 status code, not an unintended redirect or error.
- Look for orphaned pages — pages with no internal links pointing to them, which search engines may struggle to discover at all.
- Check the Coverage report in Google Search Console for pages marked "excluded" that should actually be indexed.
- Confirm there's no accidental "noindex" tag left on important pages, often left over from a staging or development version of the site.
Site speed and Core Web Vitals (items 7–11)
- Run your key pages through Google PageSpeed Insights and note both mobile and desktop scores.
- Check Largest Contentful Paint (how quickly the main content becomes visible) — slow LCP is one of the most common Core Web Vitals failures.
- Check Cumulative Layout Shift (whether elements jump around as the page loads) — often caused by images or ads without reserved space.
- Compress and properly size images — oversized, unoptimised images are one of the single most common causes of slow load times.
- Check whether unnecessary scripts or plugins are loading on every page, even where they're not needed.
Mobile usability (items 12–14)
- Test your site on an actual phone, not just a resized browser window — some layout issues only appear on genuine mobile devices.
- Confirm text is legible without zooming and buttons are large enough to tap accurately.
- Check for horizontal scrolling on mobile, usually caused by an element wider than the viewport.
Site structure and internal linking (items 15–18)
- Confirm important pages are reachable within a few clicks from the homepage, not buried deep in the site structure.
- Check that internal links use descriptive, relevant anchor text rather than generic "click here" phrasing.
- Look for broken internal links pointing to pages that no longer exist or have moved.
- Verify a logical URL structure — clean, readable URLs generally outperform long strings of parameters or IDs.
On-page technical elements (items 19–22)
- Check every important page has a unique, descriptive title tag — duplicate or missing titles confuse both search engines and searchers scanning results.
- Verify meta descriptions exist and accurately describe each page's content, even though they don't directly affect ranking, since they influence click-through from search results.
- Confirm a logical heading structure (one H1, properly nested H2s and H3s) rather than headings used purely for visual styling.
- Check for duplicate content across multiple URLs, often caused by both a "www" and non-"www" version of the site being indexed separately, or printer-friendly page duplicates.
Security and technical trust signals (items 23–25)
- Confirm the site runs on HTTPS with a valid SSL certificate — a basic trust and ranking factor that's inexpensive and standard today.
- Check for mixed content warnings (secure pages loading insecure resources), which can undermine the HTTPS setup.
- Verify structured data (schema markup) is implemented correctly using Google's structured data testing guidance, since invalid markup can be ignored entirely rather than partially credited.
Tools that make this checklist faster to work through
Screaming Frog crawls an entire site and surfaces broken links, duplicate titles, and missing meta descriptions in one pass. Google Search Console remains the single most important free tool for understanding how Google itself sees your site, including indexing status and any manual actions. PageSpeed Insights and its underlying Lighthouse report cover the speed and Core Web Vitals items directly.
How often to run through this checklist
A full pass every quarter catches most issues before they compound, with a lighter monthly check of Search Console for any new errors. Sites that undergo frequent redesigns or content migrations should run this checklist immediately after any major change, since that's when technical issues (broken redirects, orphaned pages, duplicate content) are most likely to be introduced.
An illustrative example
Picture a services business that redesigned its website eighteen months ago and hasn't technically audited it since. Working through this checklist might reveal several old blog URLs returning 404 errors after the redesign, a missing sitemap update that never included newer pages, and a handful of oversized, uncompressed images slowing the homepage significantly. None of these individually would fully explain declining traffic, but together they add up to a meaningfully weaker technical foundation than the business realises, and fixing them typically produces a modest, measurable improvement within weeks — faster than most content or link-building work, precisely because it's removing existing obstacles rather than building something new.
How to prioritise once you've found several issues at once
It's common to run through this checklist and find eight or ten issues simultaneously, which can feel overwhelming without a clear order of attack. A sensible priority sequence: fix anything blocking crawling or indexing first (items 1–6), since a page search engines can't properly access or index gets no benefit from any other improvement; then address major speed and mobile issues (items 7–14), since these affect every single visitor and every page at once; then work through structure, on-page, and security items (15–25), which tend to have a more gradual, cumulative effect rather than one dramatic fix. Trying to fix everything in a single week is rarely necessary — a steady, prioritised pace over four to six weeks is usually more realistic and just as effective.
Common mistakes when running a technical audit
- Treating every flagged item in an automated tool as equally urgent, when many "warnings" are minor and some genuinely don't apply to a given site's situation.
- Fixing issues on a staging environment and forgetting to verify the same fix actually deployed correctly to the live site.
- Running only a desktop speed test and missing that mobile performance — which matters more for most local businesses — tells a very different story.
- Auditing once and considering technical SEO "done," rather than treating it as a recurring check, especially after any site changes.
Signs your website needs this checklist urgently, not eventually
A few signals suggest technical issues deserve immediate attention rather than the next scheduled quarterly check: a sudden, unexplained drop in organic traffic with no obvious cause like a seasonal pattern; pages that used to rank reasonably well quietly disappearing from search results; a recent website redesign, platform migration, or URL structure change with no technical audit done immediately afterward; or a Search Console account that hasn't been checked in months and may be silently accumulating indexing errors. Any of these is a reason to work through this checklist now rather than waiting for the next quarterly review.
Keeping technical SEO healthy between full audits
Between full quarterly passes, a handful of lightweight habits keep most issues from accumulating unnoticed: check the Search Console Coverage and Core Web Vitals reports briefly once a month, glance at PageSpeed Insights after any significant page redesign rather than only at the next scheduled audit, and keep a simple log of any redirects or URL changes made so nothing gets lost or forgotten when tracing an issue later. None of this replaces the full 25-item pass, but it substantially reduces the chance of a serious issue sitting undetected for months before the next planned review catches it.
Who should actually own this checklist
In a small business without a dedicated in-house technical resource, this checklist often falls into a gap between "the person who manages the website" and "the person who handles marketing," with neither fully owning it. Assigning clear ownership — even if it's an external agency doing the actual audit — with a fixed quarterly date on the calendar prevents the common pattern where technical health is only reviewed reactively, after traffic has already noticeably dropped.
A quick FAQ
Do I need to fix all 25 items before doing anything else? No — prioritise crawlability and indexing issues first, since they can prevent everything else from mattering at all, then speed and mobile usability, then the more granular on-page items.
Can I do this myself, or do I need a developer? Many items (checking Search Console, running PageSpeed Insights, reviewing titles and meta descriptions) don't require coding knowledge, though fixing some issues (redirects, structured data, Core Web Vitals problems) usually does need developer involvement.
Will fixing these issues guarantee higher rankings? No — technical SEO removes obstacles rather than actively pushing you upward, so it's a necessary foundation alongside genuine content quality and relevance, not a replacement for either.
Our SEO service includes a full technical audit as standard, not an optional add-on. Book a free strategy call to get a specific read on your own site's technical health.