DefinitionThe part of SEO that makes a website easy for search engines to crawl, index and render: site speed, site structure, sitemaps, canonicals, structured data and mobile performance.
Technical SEO is the part of SEO that makes a website easy for search engines to crawl, render and index, and fast and stable for the people who use it. It covers site architecture, loading speed, status codes, canonical tags, structured data, mobile rendering and everything else that decides whether Google can reach a page, understand it and show it. Content and links are the other two pillars of SEO; technical search engine optimisation is the foundation they stand on.
The common misunderstanding is that tech SEO is a one-off checklist you tick before launch. In practice a webshop changes every week: new filters, a theme update, a plugin that rewrites URLs, a product feed that creates thousands of near-identical pages. Each of those can quietly break crawling or indexing while the shop still looks fine in a browser. Technical SEO is maintenance, not a certificate.
Why technical SEO matters for a webshop
Everything else in SEO assumes the technical layer works. You can write the best category text in the Netherlands for “elektrische fiets dames”, but if that category page returns a soft 404, points its canonical at the homepage or takes eight seconds to render on a phone, the text never gets a chance. In audits I run, the pages with the biggest revenue potential are often the ones with the most technical damage, because they sit deep in the shop with the most filters attached.
The sub-areas are easier to grasp one at a time. Crawlability is whether Googlebot can reach a URL at all; indexability is whether it is allowed to store and show that URL. Robots.txt tells crawlers which paths to skip, and the XML sitemap tells them which URLs you actually want found. Canonical tags declare which of several similar URLs is the original. Core Web Vitals measure loading speed, responsiveness and visual stability as real visitors experience them. Structured data describes products, prices and stock in a format Google can read directly, which is what earns price and review snippets. Hreflang matches each language version to the right country. Redirects and 404s decide what happens to old URLs, HTTPS protects the connection, and mobile rendering matters because Google indexes the mobile version of your shop.
Webshops add their own layer of problems on top of that. Faceted navigation (colour, size, brand, price filters) can generate millions of crawlable URL combinations from a few hundred products, which eats crawl budget and dilutes ranking signals. Duplicate product URLs appear when the same item lives under three categories with three paths. Pagination needs to let crawlers reach page 40 of a category without treating every page as a copy, and out-of-stock products need a policy rather than a silent 404. Platform migrations, say PrestaShop to Shopify or Lightspeed to WooCommerce, change every URL at once and lose rankings when redirects are incomplete. And JavaScript rendering can hide product grids, prices or internal links from Googlebot if the theme loads them client-side.
How to check technical SEO
I start with a full crawl in Screaming Frog, configured to behave like Googlebot on mobile and, for JavaScript-heavy shops, with rendering switched on. That crawl shows status codes, redirect chains, canonical targets, noindex tags, orphan pages, response times and how many clicks deep each product sits. Comparing the crawl with the XML sitemap and with the URLs that get traffic in GA4 shows where the shop and Google disagree about what exists.
Google Search Console is the second pillar because it shows Google’s side rather than mine. The Pages report lists why URLs are excluded (crawled but not indexed, duplicate without user-selected canonical, soft 404), the Core Web Vitals report groups slow URL templates, and Crawl stats shows how many requests Googlebot makes per day and how much of that goes to filter URLs or images. PageSpeed Insights gives field and lab data per template, Ahrefs Site Audit runs scheduled crawls so regressions show up between my own checks, and for larger shops I pull server logs to see which URLs Googlebot really requests, often very different from what the sitemap claims. Dygistic’s free Core Web Vitals checker and broken link checker cover the two quickest checks for a shop owner who wants a first look.
Common technical SEO mistakes
Letting filters create an infinite shop. Faceted navigation without rules means Googlebot spends its budget on “?size=42&colour=blue&sort=price” URLs instead of your products. The fix combines canonicals, noindex on filter combinations you do not want ranked, and blocking the worst parameter patterns in robots.txt.
Migrating without a redirect map. A platform switch with a new URL structure and no one-to-one 301 mapping throws away years of accumulated links and rankings in a single deploy. Shops lose most of their organic revenue this way and need months to recover what a spreadsheet would have preserved.
Trusting the browser instead of the crawler. A theme that injects product listings or prices with JavaScript can look perfect to a visitor while Googlebot sees an empty grid. Checking the rendered HTML in Search Console’s URL inspection tool is a five-minute test most shops have never done.
Deleting out-of-stock products. Removing a product page the moment stock hits zero returns a 404 for a URL that may hold backlinks and rankings. Keep the page live with a clear message and alternatives if the product returns, and redirect it to the closest category only when it is permanently gone.
How I handle technical SEO for clients
The deliverable is a prioritised technical audit, not a 200-row export of everything the crawler flagged. Every finding gets scored on impact (how much traffic or revenue it blocks) against effort (how hard it is to fix on this platform), so a shop owner sees the ten things that matter at the top and can ignore the rest. A missing alt attribute on a footer icon and a category template that noindexes itself are not the same severity, and the audit should make that obvious.
From that list I write tickets a developer can execute without me in the room: the exact URLs or template, the current behaviour, the expected behaviour, and how to verify it. On WooCommerce and PrestaShop I often implement the smaller fixes myself; on Shopify and Lightspeed the tickets focus on what the platform allows. After the sprint I run a verification crawl and compare it with the baseline, because a fix that was deployed is not the same as a fix that works. My technical SEO service runs that cycle as a one-off audit or as part of a retainer where the crawl repeats monthly.
Technical work also sets the agenda for the other pillars. There is no point writing category copy for pages that are not indexed, or buying links to URLs that redirect three times. So the audit usually comes first in a new engagement, content and internal linking follow once the foundation holds, and speed work is planned with whoever maintains the theme.
Frequently asked questions
How often should a webshop do a technical SEO audit?
A full audit once a year is the minimum for a shop that changes regularly, with a monthly scheduled crawl in between to catch regressions. Any migration, theme change or major plugin update deserves its own check before and after launch, because those are the moments when things break.
Does the platform matter: Shopify, WooCommerce, PrestaShop or Lightspeed?
The principles are identical, but the controls differ. Shopify and Lightspeed handle a lot automatically and limit what you can change, so the work is mostly about theme quality and filter handling. WooCommerce and PrestaShop give full control, which means more can go wrong and more can be fixed directly.
Do I need a developer for technical SEO?
For some of it, yes. Robots.txt, sitemaps, canonicals and redirects can often be managed with a plugin or an app, but rendering problems, speed work and template fixes need someone who can edit the theme or the server. My job is to make those tickets precise enough that a developer can do them in hours rather than days.
How long before the fixes show results?
Indexing fixes can show in Search Console within days once Google recrawls the affected pages. Ranking and revenue effects take several weeks to a few months, depending on how severe the original problem was. Speed improvements tend to show up in conversion rate before rankings.