Your website has great design. Great content. You even invest in advertising. But when you search for your business on , you don’t show up. Or worse: you show up on page 5, which is the same as not existing.
The problem, in the vast majority of cases, isn’t your content. It’s technical SEO: the invisible infrastructure of your website that allows (or prevents) from finding it, understanding it, and showing it to the people searching for you.
If you’ve never heard of technical SEO, or if you’ve heard of it but don’t know where to start, this article is for you. We’re going to explain what it is, what its core pillars are, and what you can do to stop your website from being invisible. No fluff, no unnecessary jargon, and with the concrete steps we apply when we run SEO audits for our clients.
What Technical SEO Is and How It Differs from On-Page SEO
Technical SEO is everything you do so that search engines can access your website, understand its content, and decide whether it deserves to appear in search results. It has nothing to do with the words you write or the links you earn. It has to do with how your website is built under the hood.
Think of it this way: if your website were a restaurant, on-page SEO would be the menu, the decor, and the service (what the customer sees). Off-page SEO would be the reputation, the reviews, and word of mouth. And technical SEO would be the kitchen, the facilities, the electrical wiring, and the plumbing. If the kitchen doesn’t work, it doesn’t matter how beautiful the menu is.
crawls billions of pages every day. If your website has technical problems, Googlebot (the robot that crawls the internet) may not find it, may not understand it, or may decide it’s not worth indexing. And if you’re not in ’s index, you don’t exist in search.
Raquel, the owner of a veterinary clinic, reached out to us after a year with her website online and zero organic traffic. “I had 15 articles about pet care, all well written. I couldn’t understand why Google was ignoring me.” When we reviewed her site, the problem was clear: the robots.txt file was blocking Googlebot’s access to the entire site. She was literally telling “don’t crawl me.” A 5-minute fix that cost her a year of invisibility.
Crawling: How Google Finds Your Website
The first pillar of technical SEO is crawling. Before can show your website in search results, it needs to find it and read its content. Googlebot does this by following links from page to page, like a spider moving across a web.
The robots.txt File
The robots.txt file is a text document at the root of your website that tells crawlers what they can and can’t access. It’s the first thing Googlebot reads when it visits your domain.
A misconfigured robots.txt is one of the most common and devastating errors. It can block entire sections of your website without you knowing. The official Google documentation on crawling and indexing explains in detail how to configure it correctly.
What to check:
- That it’s not blocking important pages (Disallow: /)
- That it points to your sitemap XML
- That it allows access to CSS and JavaScript ( needs to render your page)
Sitemap XML
A sitemap XML is a file that lists all the URLs on your website that you want to index. It’s like giving Googlebot a map of your site instead of leaving it to discover everything on its own.
It’s not mandatory, but it’s recommended. Especially if your website has many pages, frequently publishes new content, or has a complex navigation structure.
What to check:
- That it exists and is accessible at /sitemap.xml
- That it only includes URLs you want indexed (no 404s, no redirects)
- That it’s referenced in your robots.txt
- That it updates automatically when you publish new content
Crawl Budget
doesn’t have infinite resources. It assigns a “crawl budget” to each site. If your website has thousands of duplicate pages, broken URLs, or low-value content, wastes its budget crawling junk instead of your important pages.
For small businesses with websites under 500 pages, crawl budget is rarely an issue. But if you use WordPress with plugins that generate taxonomy URLs, author archives, and attachment pages, you could have thousands of junk URLs without realizing it. A technical SEO audit catches these crawling problems in under an hour. It’s the first step toward improving your technical SEO without touching a single line of content.
Indexing: Getting Google to Include You in Its Results
Just because crawls your website doesn’t mean it will index it. Crawling is step 1. Indexing is step 2: decides whether your content deserves to be in its search index. This is where technical SEO complements on-page SEO: indexing depends on both technical infrastructure and the quality and structure of your content.
Canonical URL
The canonical URL tag tells which is the “official” version of a page when duplicates exist. For example, if the same page can be accessed at yourdomain.com/product and yourdomain.com/product?ref=email, you need a canonical indicating which one is the original.
Without canonicals, can:
- Index the wrong version of your page
- Dilute authority across duplicates
- Get confused about which page to show in results
Meta Robots
robots tags (noindex, nofollow) control which pages get indexed and which links get followed. If someone added a “noindex” to an important page during development and forgot to remove it, that page will never appear in .
It’s more common than you think. We see it in audits at least once a month.
Google Search Console
’s free tool for verifying your website’s indexing. It tells you exactly which pages are indexed, which have errors, and which have been excluded. If you don’t have Search Console set up, you’re flying blind.
If you want to understand how is changing with artificial intelligence and how that affects SEO, we have a full article on SEO and AI that complements this guide.
Core Web Vitals: Performance and User Experience
Core Web Vitals are the metrics uses to measure your website’s user experience. They’ve been a ranking factor since 2021, and in 2026 they matter more than ever because rewards fast websites in both organic results and AI Overviews.
LCP (Largest Contentful Paint)
Measures how long it takes for the largest visual element on the page to load (usually the main image or the largest block of text). The target is under 2.5 seconds.
How to improve it:
- Optimize images (WebP/AVIF, correct sizes)
- Use lazy loading for off-screen images
- Minimize render-blocking CSS and JavaScript
- Use a CDN (Content Delivery Network)
INP (Interaction to Next Paint)
Replaced the old FID. Measures how quickly your website responds when the user interacts (click, tap, keyboard). The target is under 200 milliseconds.
How to improve it:
- Minimize third-party JavaScript
- Break long tasks into smaller chunks
- Prioritize interactivity for visible content
CLS (Cumulative Layout Shift)
Measures unexpected layout shifts while the page loads. That moment when you’re about to click a button and the content jumps because an ad loaded above it. The target is under 0.1.
How to improve it:
- Define width and height on all images
- Reserve space for ads and embeds
- Use font-display: swap for custom fonts
Page Speed Matters More Than You Think
Page speed isn’t just a technical metric. According to web.dev, every additional second of load time reduces conversions by 7%. If your website takes 5 seconds to load instead of 2, you’re losing customers every single day.
Diego, the director of an online sporting goods store, came to us frustrated. “We were spending 2,000 euros a month on Google Ads, but our bounce rate was 75%.” When we measured his website on PageSpeed Insights, the LCP was 6.2 seconds. Users clicked the ad, waited, and left. After optimizing images, implementing lazy loading, and moving to a hosting provider with a CDN, the LCP dropped to 1.8 seconds. The bounce rate fell to 42% and sales went up 35% without changing a single euro in ad spend.
If your website is built with modern technology like Next.js, these problems are far less common. The framework renders on the server, automatically optimizes images, and uses a global CDN. We go into detail on this in our guide on how much it costs to build a website.
Website Architecture and Structure
URL Structure
Clean, descriptive URLs help both and users. yourdomain.com/services/web-development is better than yourdomain.com/?page_id=247.
Best practices:
- Lowercase, with hyphens (not underscores)
- Include the keyword when it feels natural
- Short and descriptive (3-5 words)
- No unnecessary parameters
Heading Hierarchy
H1, H2, H3… aren’t just text sizes. They’re the semantic structure of your content. uses them to understand the information hierarchy: what’s important, what’s secondary, what’s a detail. If your headings don’t follow a logical order, doesn’t understand your page. One H1 per page (the title), H2 for main sections, H3 for subsections.
Structured Data and Schema Markup
SEO structured data is JSON-LD code you add to your website so understands the meaning of your content, not just the words. Implementing structured data is one of the highest-ROI tasks in technical SEO because the effort is minimal and the impact on visibility is immediate. You’re telling it “this is an article,” “this is a product with this price,” “this is an FAQ.”
With structured data, you can earn rich snippets in search results: star ratings, prices, expandable FAQs, breadcrumbs. More visibility = more clicks.
Security: HTTPS
If your website still uses HTTP instead of HTTPS, marks it as “not secure” and penalizes it in rankings. An SSL certificate is free (Let’s Encrypt) and most hosting providers install it with one click. There’s no excuse not to have it. On top of that, HTTPS improves page speed thanks to the HTTP/2 protocol, which only works over secure connections. This directly impacts your Core Web Vitals and, therefore, your rankings.
Technical SEO Checklist for Your Website
Use this list to verify the fundamentals:
- robots.txt accessible and without incorrect blocks
- Sitemap XML present, up to date, and submitted to Search Console
- Search Console set up and verified
- HTTPS active with a valid SSL certificate
- LCP under 2.5 seconds
- INP under 200 milliseconds
- CLS under 0.1
- Mobile-first: website functional and fast on mobile
- Canonical URLs configured to prevent duplicates
- No noindexed pages that should be indexed
- No 404 errors on important pages
- Structured data (JSON-LD) implemented
- Headings with correct hierarchy (H1 > H2 > H3)
- Images optimized with descriptive alt text
- Page speed verified on PageSpeed Insights
If you answered “no” to three or more points, your website needs attention. If you want to run a full diagnostic with free tools, we have a guide to detect SEO problems before spending a euro. And if you’d rather have a professional team handle it, at LetBrand we run technical SEO audits for 200 euros that cover all of these points and more.
Technical SEO in the Age of AI
In 2026, technical SEO isn’t just for . AI models (, , ) also crawl websites to generate answers. And they have the same technical requirements: they need to be able to access your content, understand its structure, and find verifiable data.
Structured data is especially important for AI. A language model that finds your content properly marked up with JSON-LD is far more likely to cite you as a source in its answers. It’s the difference between the AI saying “according to specialized sources…” and “according to LetBrand…”
If you want to dig deeper into how AI is changing the rules of SEO, read our article on SEO and artificial intelligence.
Technical SEO Is the Foundation. Everything Else Is Built on Top
Let’s recap the fundamentals:
- Technical SEO is the invisible infrastructure that allows to find, understand, and display your website
- Crawling (robots.txt, sitemap XML) is the first step: making sure can access your site
- Indexing (configuring each canonical URL, meta robots, Search Console) is the second step: getting to include you. Without proper indexing, all your on-page SEO is invisible
- Core Web Vitals (LCP, INP, CLS) measure user experience and directly affect rankings
- Structured data gives you extra visibility in search results and makes you citable by AI
- Page speed affects conversions, SEO, and user experience
You can write the best content in the world. If your website’s technical SEO is broken, that content is invisible. It’s like having the best product in a store with no door.
The good news: most technical SEO problems are fixable. Many in a matter of hours. The first step is knowing where they are.
Every day your website has technical problems is a day you’re losing customers who are looking for you but can’t find you.
Want to know exactly what technical problems your website has and how to fix them? Book an SEO audit. 200 euros, no strings attached. We give you a report with every problem, its impact, and the exact steps to fix it. If we don’t find anything to improve, you get your money back.
