Technical SEO is the invisible work that makes all the difference. A site with exceptional content and quality links can stay stuck on page 3 if its technical foundations are flawed. Google must be able to find, crawl, understand and rank every page of your site without friction.
A technical SEO audit is a complete analysis of your website's infrastructure: loading times, URL structure, canonical tags, error handling, page indexing, mobile compatibility, structured data. It is the mandatory starting point of any serious SEO strategy — in Belgium as everywhere else.
At Ligne 1, our technical SEO experts master the entire chain: from Screaming Frog analysis to Schema.org implementation, including Core Web Vitals optimization and advanced robots.txt configuration. We turn your site into a perfect indexing machine.
of mobile visitors abandon a site that takes more than 3 seconds to load
organic traffic gained on average after fixing critical technical errors
The technical SEO audit: a full X-ray of your site
A technical SEO audit is much more than an automated scan. It is an in-depth, manual analysis of all the technical parameters that influence Google's ability to crawl, index and rank your site. At Ligne 1, every technical audit is carried out by a senior SEO expert — not delegated to an automated tool.
Our audit protocol covers several hundred checkpoints grouped into six main families. At the end of the audit, you receive a detailed report with every issue identified, its estimated impact on your search visibility, and an action plan prioritized by fixing effort and potential gain.
The six areas of analysis in our technical audit
- Crawlability and indexing — Analysis of the robots.txt file, the XML sitemap, noindex/nofollow directives, orphan pages, the crawl budget allocated by Google and Google Search Console reports (crawl errors, excluded pages, indexing warnings).
- Performance and Core Web Vitals — Measurement of Google's three official metrics (LCP, INP, CLS) on mobile and desktop via PageSpeed Insights, Lighthouse and the Chrome UX Report. Identification of every resource that slows rendering: unoptimized images, blocking JavaScript, unused CSS, poorly loaded fonts, slow third-party scripts.
- URL architecture and structure — Verification of URL logic (readable, free of unnecessary parameters, no duplicates), navigation depth (max 3 clicks from the home page), internal linking, redirect consistency and the absence of redirect chains.
- HTML tags and metadata — Audit of title tags (uniqueness, length, relevance), meta descriptions, Hn tags (a single H1 per page, correct hierarchy), image alt attributes, canonical tags, Open Graph tags and Twitter Cards.
- Mobile compatibility and HTTPS — Mobile-first index testing (Google indexes the mobile version first), verification of the SSL/TLS certificate, mixed content, the absence of intrusive interstitials and the accessibility of touch elements.
- Schema.org structured data — Inventory and validation of all JSON-LD markup in place, error detection with Google's Rich Results Test, identification of relevant schema types not yet implemented on your site.
Our technical SEO audit identifies on average 47 improvement points on a medium-sized site. Fixing the 5 to 10 critical priorities often generates a visible traffic gain as early as the following month.
Core Web Vitals in Belgium: your passport to the top positions
Since May 2021, the Core Web Vitals have been official ranking factors in Google's algorithm. These three metrics assess the real experience of users on your site — not lab measurements, but the performance recorded on the devices of real Belgian visitors. A site that fails these tests is penalized in search results against competitors that pass them.
LCP — Largest Contentful Paint (display speed)
LCP measures the time needed for the largest visible element of your page (often a hero image or a main heading) to be fully displayed. An LCP under 2.5 seconds is considered "good" by Google. Between 2.5 and 4 seconds: "needs improvement". Beyond that: "poor".
The common causes of a poor LCP that we diagnose and fix:
- Hero images that are uncompressed and not converted to WebP or AVIF
- No preloading (preload) of the main image
- Slow server (Time to First Byte above 600 ms)
- Render-blocking resources (JavaScript and CSS in the head without defer/async)
- No CDN with a point of presence in Europe
INP — Interaction to Next Paint (responsiveness)
INP (which replaced FID in March 2024) measures how responsive your page is to user interactions: clicks, taps, keyboard input. An INP under 200 ms is the target to reach. A high INP translates into a jerky, frustrating experience that hurts your SEO as much as your conversion rate.
Main causes of a poor INP:
- Long JavaScript tasks (Long Tasks) blocking the main thread
- Overloaded WordPress plugins or third-party scripts (chatbots, advertising trackers)
- Excessive client-side rendering (unoptimized Single Page Applications)
- Poorly optimized event handlers
CLS — Cumulative Layout Shift (visual stability)
CLS quantifies the unexpected visual shifts that occur while a page loads: elements that suddenly move because an image or an ad loads after the text. A CLS under 0.1 is the target. These shifts cause accidental clicks and severely degrade the mobile experience.
- Always specify width/height dimensions on every image and video
- Reserve space for ads and iframes with min-height
- Preload web fonts with font-display: swap
- Avoid injecting dynamic content above existing content
Only 33% of Belgian websites pass all the Core Web Vitals tests according to our latest market study. It is your chance to outrank two-thirds of the competition simply by fixing your technical performance.
URL architecture and internal linking: structure to dominate
Your website architecture determines how Google distributes and perceives authority between your pages. A well-designed structure lets Googlebot crawl your whole site efficiently, ensures your most important pages receive the most SEO link equity (link juice) and gives your visitors intuitive navigation.
Principles of an optimal URL architecture
- Readable, descriptive URLs — Prefer /services/technical-seo-audit/ to /page?id=42&cat=3. URLs should contain the target keyword, be lowercase, free of special characters, and use hyphens (not underscores) as separators.
- Thematic silo structure — Organize your pages into coherent thematic groups: /seo/, /seo/technical/, /seo/semantic/ rather than a flat mix. This hierarchy strengthens the topical authority of each silo.
- Maximum depth of 3 clicks — Every important page should be reachable in 3 clicks at most from the home page. Pages buried 5 or 6 clicks deep receive very little authority and are rarely well indexed.
- Canonical URL management — On e-commerce sites or sites with filters (color, size, price), each URL variation must point to the canonical URL to avoid diluting SEO link equity and creating duplicate content.
- Clean 301 redirects — Every deleted or moved page must get a permanent 301 redirect. 404 errors and redirect chains (301 → 301 → 301) waste crawl budget and dilute authority.
Strategic internal linking
Internal linking is the set of links that connect your pages to each other. It is one of the most underestimated and most powerful SEO levers. A well-placed internal link passes authority to the target page, tells Google the relative importance of each page and guides users toward conversions.
Our approach to internal linking at Ligne 1:
- Contextual links with rich anchors — Every internal link should have a descriptive anchor containing the keyword of the destination page. Avoid generic anchors such as "click here" or "read more".
- Hub & spoke model — Each pillar page (hub) is linked to its satellite articles (spokes) and vice versa. This star-shaped structure concentrates authority on the most important pages of each thematic silo.
- Orphan link audit — We identify and link every page of your site that receives no internal link. These orphan pages are invisible to Google, even if they exist in your sitemap.
- Structured breadcrumbs — Breadcrumbs strengthen internal linking and allow the navigation path to be displayed in Google snippets, which improves click-through rate.
Crawl budget: make every Google visit a worthwhile investment
Crawl budget is the amount of resources Googlebot allocates to crawling your site over a given period. Every site has a limited budget: Google cannot crawl all your pages on every visit. If your site contains thousands of useless pages (URLs with parameters, pagination pages, filtered pages, duplicate pages), Googlebot crawls them at the expense of your important pages.
Crawl budget management is critical for large sites (e-commerce, directories, news sites) but also for SMEs whose strategic pages are never indexed because of a poor configuration.
Crawl budget optimization strategies
- Well-controlled robots.txt — Block URLs with no SEO value: login pages, internal search results pages, URLs with tracking parameters (utm_source, etc.), admin pages. Never block the CSS/JS resources Google needs to render pages.
- Meta robots directives — Use noindex on duplicate pages, post-form thank-you pages, print pages and low-value archives. Combined with robots.txt, this steers Google toward what matters.
- Pagination and infinite scroll — Implement pagination correctly (rel=next/prev is deprecated — prefer a dedicated indexing sitemap) and handle infinite scroll so that Google can reach paginated content.
- Server speed (TTFB) — A high Time to First Byte slows crawling. Google allocates less budget to slow sites. Target: TTFB under 200 ms with a host in Europe (OVH, Combell, Kinsta).
- Clean internal links — Eliminate links to 404 pages, chained redirects and JavaScript links that bots cannot access. Every broken link wastes a share of the crawl budget.
- Dynamic, clean XML sitemap — The sitemap should list only the pages to be indexed (excluding noindex, 301 and 404 pages). Update it automatically with every new publication. Submit it in Google Search Console.
On an e-commerce site with 5,000 products, we found that 40% of the URLs crawled by Google had no SEO value (filters, parameters, empty pages). After cleanup, the important product pages saw their indexing frequency triple within 8 weeks.
Schema.org structured data: speak the language of Google (and of AI)
Schema.org structured data consists of code tags (in JSON-LD, the format recommended by Google) that you add to the HTML of your pages to describe their content explicitly to search engines. Where Google would otherwise have to guess that your page is about a product, an event or a recipe, schema.org tells it directly — without ambiguity.
Beyond classic SEO, structured data has become essential for appearing in the AI answers of Google (AI Overviews), ChatGPT, Gemini and Perplexity, which rely heavily on structured data to cite reliable sources.
The most impactful schema types for Belgian businesses
- LocalBusiness / ProfessionalService — The most important markup for Belgian SMEs. It tells Google your name, address, phone number, opening hours, services and the geographic area you serve. Essential for appearing in the Google local pack.
- FAQPage — Every question-and-answer block on your site can be marked up as FAQPage. Result: your Q&As display directly under your Google result, taking up to 4 times more space in the SERP and increasing CTR by 20 to 30%.
- Product / Offer — For e-commerce, this markup displays price, availability and reviews directly in Google Shopping and organic results. Indispensable for product page visibility.
- Article / BlogPosting — Mark up your blog articles with the author, publication and modification dates, and publisher. Strengthens E-E-A-T signals and supports display in Google Discover.
- BreadcrumbList — Displays the navigation path in Google snippets (Home › Services › Technical SEO), which improves result readability and click-through rate.
- Review / AggregateRating — Customer review stars in Google results considerably increase the appeal of a snippet. To be combined with verified review platforms (Trustpilot, Google Reviews).
- HowTo — For tutorial content and step-by-step guides, this schema can trigger an enhanced display with numbered steps directly in Google results.
- VideoObject — Mark up your embedded YouTube videos to help them appear in Google video results and Google Images.
Validating and maintaining structured data
A poorly implemented schema.org can generate errors reported in Google Search Console and, in serious cases, prevent rich snippets from displaying. At Ligne 1, every implementation is validated with Google's Rich Results Test and the schema.org Schema Markup Validator. We also run regular audits to detect regressions when the site is updated.
Mobile-first indexing: your site judged as your mobile visitors see it
Since 2020, Google has used the mobile-first index exclusively to rank all websites. In practice, this means Google crawls and evaluates your site using its mobile bot (Googlebot Smartphone) — not the desktop bot. If your mobile version is less complete, slower or poorly structured compared with your desktop version, it is your mobile performance that determines your Google rankings for all users.
Mobile-first checklist for optimal search visibility
- Equivalent content on mobile and desktop — Do not hide content on mobile for aesthetic reasons. Google only indexes what is visible on mobile. If your desktop page contains 1,500 words and your mobile page 400, Google indexes 400 words.
- Responsive design tested on real devices — Responsive design is not enough. We test your site on a range of real Android and iOS devices (not only in emulation) to detect display bugs that simulators miss.
- Touch element size — Buttons, links and menus must have a tap area of at least 48x48 pixels to be usable with a finger. Google penalizes sites with touch elements that are too small or too close together.
- Non-intrusive interstitials — Popups that cover the main content on mobile violate Google's guidelines. Exceptions: GDPR cookie banners and legally required age verification. Any other intrusive popup risks a manual penalty.
- Images adapted with srcset — Use the srcset attribute to serve images suited to each device's resolution and screen size. A mobile phone does not need to download an image 2,400 px wide.
- Readable fonts and colors — Minimum font size of 16px on mobile. Sufficient contrast (WCAG AA ratio at minimum). Avoid text over image backgrounds without contrast control.
In Belgium, 67% of web traffic comes from mobile. If your site offers a degraded experience on smartphones, you lose two-thirds of your potential customers — and your Google rankings along with them.
Meta tags, canonicals and error handling
Meta tags are instructions that are invisible to visitors but vital for search engines. A poorly written title tag, a duplicated meta description or an incorrect canonical tag can undo months of SEO effort. Here are the critical points we systematically audit and optimize.
Title tag — the first SEO impression
The title tag is the HTML element with the most influence on Google rankings for a given page. It appears as the clickable title in search results. Our standards at Ligne 1:
- Optimal length: 55 to 65 characters — Beyond that, Google truncates and may rewrite the title with its own version (which already happens in 61% of cases according to recent studies).
- Main keyword first — Place the target keyword as early as possible in the title. Google gives more weight to words at the beginning of the title.
- Absolute uniqueness — Every page must have a different title. Duplicate titles dilute authority and confuse Google about which page to rank for which query.
- Appeal to humans — A good title makes people want to click. Include a differentiating element (number, benefit, location) while staying natural.
Meta description — the silent salesperson
The meta description does not directly influence rankings but it determines your click-through rate (CTR). A high CTR sends a positive signal to Google. Our criteria: 145 to 160 characters, presence of the target keyword, a clear value proposition, an implicit call to action. Every page must have a unique meta description.
Canonical tag — eradicating duplicate content
The canonical tag (rel="canonical") is the standard solution for duplicate content problems: pages accessible with and without www, with and without a trailing slash, over HTTP and HTTPS, or through different URL parameters. An incorrect canonical implementation can create loops or point to nonexistent pages — we check every canonical individually.
Handling 404 errors and 301 redirects
404 errors (pages not found) have two negative impacts: they waste crawl budget and create a poor user experience. Our management protocol:
- Full inventory of 404s via Google Search Console, Screaming Frog and server logs
- 301 redirect to the most relevant page for every 404 that still receives traffic or backlinks
- Creation of a custom 404 page with internal navigation to limit the bounce rate
- Monthly monitoring of new errors to react quickly
Your questions about technical SEO
What is technical SEO and why is it important?
Technical SEO covers all the optimizations that make it easier for Google to crawl, understand and index your site. Without solid technical foundations, even the best content in the world will not be properly indexed or ranked. It is the foundation on which every SEO strategy rests: page speed, URL architecture, crawl management, structured data, mobile compatibility. At Ligne 1, the technical audit is always the first step of any SEO engagement.
What are Core Web Vitals and how can they be improved?
Core Web Vitals are three official Google metrics that assess the real user experience on your site: LCP (display speed of the main content, target < 2.5s), INP (responsiveness to interactions, target < 200ms) and CLS (visual stability, target < 0.1). To improve them, you need to compress images, optimize JavaScript, use a CDN, configure caching correctly and size elements properly. Ligne 1 carries out a full audit and implements all the necessary technical fixes.
How can I tell whether Google is indexing all my pages properly?
The most reliable method is to use Google Search Console (free) in the "Pages" tab: it shows the number of indexed pages, the excluded pages and the reasons for exclusion (noindex, 404 error, duplicate without canonical, insufficient content…). You can also type site:votre-domaine.be into Google to see the number of listed pages. If you notice large gaps with your actual number of pages, a crawl audit is needed. Ligne 1 offers a full Search Console analysis as part of its technical audit.
What is crawl budget and does it matter for my site?
Crawl budget is the number of pages Google crawls on your site within a given period. For small sites (fewer than 500 pages), it is generally not a critical issue. However, for e-commerce sites, directories or sites with a large amount of content, mismanaging crawl budget means your most important pages are crawled less often — and new pages take longer to be indexed. Optimizing crawl budget involves: a well-configured robots.txt, clean URLs without unnecessary parameters, an up-to-date sitemap and high server speed.
How does Schema.org structured data improve my search visibility?
Schema.org structured data lets Google understand precisely the type and content of each page. It unlocks rich snippets (enhanced results) in the SERP: review stars, expandable FAQs, product prices, recipe preparation times… These enhancements increase your click-through rate by 20 to 35% on average without changing your position. They are also essential for appearing in the answers of generative AI such as Google AI Overviews, ChatGPT and Gemini.
Is my site penalized if I don't have an optimized mobile version?
Yes. Since 2020, Google has used the mobile-first index exclusively. This means the mobile version of your site is the one crawled and evaluated for ranking — for all users, desktop included. A site poorly adapted to mobile will be systematically penalized against competitors that have taken care of their mobile experience. Responsiveness (responsive design), mobile speed, touch element size and the absence of intrusive interstitials are criteria Google evaluates at every crawl.
Your site deserves flawless technical foundations.
Request your technical SEO audit and discover the invisible obstacles blocking your Google visibility.