Technical SEO checklist: what to check once and what to keep watching
A technical SEO checklist covers what lets search engines crawl, render and index a site: robots.txt, status codes, canonicals, sitemaps, internal links, templates and the server underneath. Most checklists treat every item the same way, but they fall into two groups. Some you check once during an audit and revisit only when the site is rebuilt. Others can change on any deploy, and those cause the sudden drops.
This one is split that way. The first half is for a new site or a new client, the second for every week after.
Part one: the initial audit
These items depend on how the site was built. Run a crawler such as Screaming Frog or Sitebulb, go through Search Console, and fix what you find.
- http and https, www and non-www each resolve to one canonical host with a single 301
- URL parameters don't create duplicate versions of the same page
- redirect chains flattened, old URLs pointing straight at the final destination
- internal links pointing to 200 URLs, not to redirects or 404s
- important pages reachable in a few clicks, no orphan pages that matter
- main content present in the rendered HTML (check with the URL Inspection live test)
- mobile layout complete, since Google indexes the mobile version
- structured data valid in the Rich Results Test, where you use it
- Core Web Vitals and Page indexing reports in Search Console read reason by reason
Once fixed, most of these stay fixed. They regress with a redesign, a CMS change or a migration, and each of those deserves its own audit.
Part two: what can change on any deploy
These are small settings, often a single line, that a plugin update, a CMS toggle or a config copied from staging can change without anyone touching the content.
Indexing directives
In robots.txt, look for a new Disallow: / or rules blocking CSS and JavaScript folders, and make sure the file never returns a 5xx: Google pauses crawling while it can't read it. Check the noindex meta tag on templates that should be indexed, and the same directive sent as an HTTP header, which you only see with curl -I or DevTools (X-Robots-Tag explained). On WordPress, the "Discourage search engines from indexing this site" box under Settings, Reading is the classic one.
Canonicals and sitemap
Each canonical should point to the page itself or its real equivalent, never to the staging domain or the home page. The XML sitemap should list only indexable URLs that return 200, and important pages shouldn't drop out of it after a release.
On-page tags
Title, meta description and H1 present, unique and not overwritten by a template change. On multilingual sites, the lang attribute and the hreflang annotations must match between versions (see the html lang attribute).
Server, certificate and domain
Home page and key templates returning 200, without intermittent 5xx. SSL certificate valid with time to spare. Domain renewal date known and auto-renew on, because an expired domain takes the whole site out of the index.
Tracking
GA4, GTM and ad pixels still present with the right IDs. Not a ranking factor, but if tracking breaks you can't measure the next drop.
How often to run each half
Part one at onboarding, after a migration and once a year. Part two ideally every day: a noindex pushed on Friday afternoon and spotted on Monday has had a weekend of crawling. If a site has vanished from Google altogether, the diagnosis in site removed from Google starts with these same checks.
Automating the second half
Deltio covers most of part two. Its SEO scanner reads title, meta description, H1, canonical, lang, hreflang and noindex (meta tag and X-Robots-Tag) on each URL and alerts you when they change between scans. robots.txt is compared with its previous version line by line, the sitemap is snapshotted daily, uptime is checked every 10 minutes, SSL and domain expiry are flagged in advance, and marketing tags are tracked when they appear, disappear or change ID. Alerts arrive by email or Slack.
Part one stays with your crawler: Deltio doesn't crawl the whole site, measure page speed or read Search Console.
Starter costs £24 a month, £20 billed annually, and you can try it free for 14 days.
Frequently asked questions
- What is the difference between a technical SEO audit and technical SEO monitoring?
- An audit is a one-off review, usually with a crawler, that finds structural problems at a point in time. Monitoring checks a smaller set of settings continuously, such as robots.txt, noindex, canonicals and uptime, so that a change made after the audit is spotted within a day rather than at the next review.
- Which technical SEO issues cause the biggest sudden drops?
- The ones that affect a whole template or the whole site at once: a Disallow: / in robots.txt, a noindex left over from staging, canonicals pointing to another domain, long server outages and an expired domain. Each can be introduced by a single change.
- Is page speed part of a technical SEO checklist?
- Usually yes. Core Web Vitals are part of how Google assesses page experience, and the Search Console report groups failing URLs by issue. It fits the audit half of the checklist, since it changes with code and hosting rather than with a single setting.
- What should I check right after a website release?
- Open robots.txt, run curl -I on a few key templates to see the status code and any X-Robots-Tag header, view the source for meta robots and canonical, and check that the sitemap still lists the important URLs. Then confirm the tracking tags are still on the page.
- Does Deltio replace a crawler like Screaming Frog?
- No. Deltio watches a defined set of SEO elements, plus robots.txt, sitemap, uptime, SSL, domain and tags, and alerts you when they change. It doesn't crawl the whole site, find broken links or measure page speed, so a crawler is still the tool for audits.