Technical SEO Health Check for 2025 (LLM-Ready Guide)

Technical SEO in 2025 isn't just about appeasing Google's algorithm; it's about future-proofing your site for Large Language Models (LLMs), ensuring lightning-fast user experiences, and unlocking next-generation SERP features. Whether you're running a massive e-commerce platform or a nimble SaaS startup, your site's technical foundation is the bedrock upon which both visibility and engagement are built. A weak foundation means your content, no matter how good, may never get the attention it deserves.

So, what does a truly comprehensive, LLM-ready SEO health check look like in today's digital landscape? It's a deep dive into the core mechanics of your site, ensuring every component is optimized for both human users and sophisticated AI systems. Let’s break down the essential elements you need to inspect and perfect.

A slow website isn't an inconvenience; it's a liability. Performance directly impacts user behavior, search rankings, and, most importantly, your bottom line. Google's Core Web Vitals (CWV) are a set of metrics that measure a site's speed, responsiveness, and visual stability, and they've become a critical ranking factor. Core Web Vitals optimization is no longer optional; it's a critical component of modern SEO.

The reality is that a significant number of websites are failing these fundamental checks. Only about a third of all websites currently pass Google's Core Web Vitals. To be considered "passing," your site must meet these three key thresholds:

• Largest Contentful Paint (LCP): This measures how long it takes for the largest image or text block to become visible on the screen. It should load in 2.5 seconds or less.
• Interaction to Next Paint (INP): This metric gauges a page’s overall responsiveness to user interactions, such as clicks or taps. Your site needs to respond in 200 milliseconds or less.
• Cumulative Layout Shift (CLS): This measures the visual stability of your page. Your score should be 0.1 or lower.

Achieving this requires dedicated CWV LCP/INP/CLS tuning, which involves optimizing code, images, and server response times to ensure a seamless experience.

The average website load time is a stark reminder of why speed matters. A typical desktop site loads in around 2.5 seconds, while a mobile site takes a staggering 8.6 seconds. This delay has a direct, measurable impact on user behavior and conversions:

• A mere 1-second delay in page load time can cause a 7% drop in desktop conversions and a 20% drop in mobile conversions.
• Over half of all users (53%) will abandon a mobile page if it takes more than 3 seconds to load.
• Incorporate bullet points and numbered lists to break down complex ideas into digestible chunks. AI often uses these for snippet extraction.
• A 2-second delay can cause your bounce rate to skyrocket by 103%.

The payoff for prioritizing speed is undeniable. Sites that successfully pass Core Web Vitals see a 24% higher engagement rate, proving that a fast site leads to a more satisfied, and more loyal, audience. .

Google's shift to a mobile-first indexing model is a fundamental change that's now a reality for the vast majority of websites. This means Google primarily uses the mobile version of your content for crawling, indexing, and ranking. A thorough Mobile-first indexing audit is essential to ensure your site is properly configured for this reality. If your mobile experience is subpar, your entire site's visibility is at risk.

The statistics paint a clear picture of why a mobile-first mindset is essential:

• Over 70% of websites are now crawled using a mobile-first approach.
• Mobile devices account for approximately 60% of all global website traffic.
• Pages that are fully mobile-friendly are 67% more likely to rank on the first page of search results.
• The average mobile bounce rate (56.8%) is significantly higher than the average desktop bounce rate (50%), indicating that users are less patient with poor mobile experiences.

To succeed, you must optimize every single element of your site for mobile. From touch-friendly navigation to properly sized text and images, every pixel needs to be considered. Failing to do so could result in your site being completely overlooked in search results.

In 2025, a secure website isn't an added feature; it's a fundamental requirement. HTTPS (Hypertext Transfer Protocol Secure) provides a secure connection between your user's browser and your website, protecting their data and building trust. A complete HTTPS security validation is a mandatory part of any technical health check.

This is a non-negotiable ranking factor. A staggering 95% of top-ranking sites on Google use HTTPS. Yet, a significant number of domains still have flawed implementations. For example, 88% of domains have issues with their HTTP to HTTPS redirects, a problem that can create duplicate content issues and confuse search engine crawlers. Non-secure (HTTP) pages also suffer from higher user abandonment, with bounce rates up to 50% higher than their secure counterparts.

Your technical health check must include a thorough audit of your HTTPS setup. Ensure your SSL certificate is valid and not expired, your redirects from HTTP to HTTPS are clean and direct, and your overall security configuration is airtight.

This is where the future of SEO comes into focus. Structured data, or Schema markup, is a standardized format for providing information about your content to search engines and AI models. This isn't just about getting rich snippets anymore; it's about making your content understandable to the next generation of LLMs.

Not all structured data formats are created equal. The industry standard and the format most preferred by LLMs like ChatGPT and Google Gemini is JSON-LD structured data markup. This format is easy to implement and maintain, as it doesn't require direct changes to your site's HTML. Nearly half of all structured data (49.7%) now uses JSON-LD, and for good reason. For optimal Schema.org LLM markup, JSON-LD is the clear winner. If you want your content to be accurately referenced and used by AI assistants and other advanced systems, using JSON-LD is no longer optional.

Crawlability is the process by which search engines discover and read your site's content. Indexing is the process of storing that content in their database. If a search engine can't crawl your site, it can't index your content, and you won't show up in search results. Unfortunately, this is a common point of failure for many websites. Implementing AI-friendly crawlability fixes is the key to ensuring your site is fully discoverable.

A quarter of all websites have some form of crawlability problem. The most common issues include:

• Misconfigured robots.txt files that block search engines from accessing important pages.
• Poor internal linking structures that make it difficult for crawlers to discover new content.
• 3xx redirect chains, which are the most frequent crawl issue, affecting 95.2% of sites. These chains force crawlers to follow multiple redirects to reach a destination, wasting crawl budget and slowing things down.
• Broken links, which account for 15% of all crawl errors and lead to frustrating 404 pages.
• Missing H1 tags, which are absent on 59.5% of pages. This confuses search engines about the page's main topic and can harm SEO.

One of the key metrics is dwell time, which measures how long visitors stay on your page. Longer dwell times signal to AI that your content is valuable, engaging, and satisfies the user’s query. On the other hand, a short visit may suggest your page didn’t meet expectations.

A few simple, strategic fixes can make a massive difference:

• Optimize and submit a clean XML sitemap. This can improve crawl efficiency by 6%.
• Eliminate all 3xx redirect chains. Fix the underlying issues to prevent unnecessary redirects.
• Add strong, relevant internal links to help crawlers and users navigate your site.
• Fix all broken links and ensure every single page has a clear and logical heading hierarchy, starting with a proper H1 tag.

Images can be your website's biggest speed killer or a powerful SEO asset. The key is to optimize them correctly. Optimized images can reduce your load times by up to 50%, yet many sites fail to implement basic best practices.

For example, 80.4% of sites don’t use alt attributes on their images. This is not only a major accessibility issue for users with visual impairments but also a significant missed opportunity for SEO. Dedicated Image alt-text optimization is crucial. Alt text provides context to search engines about the content of an image, helping them understand and index it correctly. This is more important than ever, as image search now accounts for 22.6% of all Google queries.

To get this right, you need to compress your images to the smallest possible file size without sacrificing quality and always include descriptive, keyword-rich alt text on every image.

If your website serves a global audience with content in multiple languages, you need to manage your international SEO correctly. The tool for this is the hreflang tag, which tells search engines the relationship between pages in different languages or for different regions.

However, hreflang implementation is notoriously tricky. A staggering 67% of domains have hreflang implementation errors, which can cause a host of problems, including content cannibalization and confusing search engine bots. When done right, hreflang can boost your regional rankings by 20%. When done wrong, it can actively harm your visibility. Make sure your hreflang tags are validated and correctly configured.

You wouldn't leave potholes in your physical store, would you? 404s are the digital equivalent. A 404 page is a dead end for both users and search engine crawlers. A high number of these errors can cause a 12% drop in user trust, making visitors less likely to return. Cleaning them up can improve your crawl rate by 18%.

While redirects are sometimes necessary, don't use them as a band-aid for broken pages. Implement a strategy of 404 redirect hygiene. Fix the root of the problem instead of creating long redirect chains, which can hurt performance and user experience. Regularly audit your site for 404s and implement proper, permanent redirects (301 redirects) only when a page has permanently moved.

For websites with a global audience, a Content Delivery Network (CDN) is a non-negotiable tool. A CDN is a network of servers distributed geographically that delivers web content to users based on their location. This significantly reduces latency and ensures consistent performance worldwide.

Implementing a CDN can:

• Reduce latency by 27%.
• Slash load times by 50%.
• Result in a 15% lower bounce rate.

This dedicated CDN global performance boost is a no-brainer if you're targeting customers in multiple countries, as it ensures a fast and reliable experience for everyone, regardless of where they are.

If you view technical SEO as a simple checklist item, you’re missing the bigger picture. The return on investment (ROI) for technical SEO is incredibly high and fast. The average ROI is a remarkable 117%, with a break-even point in just 6 months. This is significantly faster than other SEO efforts, like thought-leadership content, which takes 33% longer to show returns, and basic content marketing, which is 60% slower. The payoff for a healthy, technically sound website is real and measurable.

To ensure your site is ready for both search bots and AI models, here's your must-do checklist:

• Pass Core Web Vitals: Ensure your LCP is under 2.5s, INP is below 2ntin00ms, and CLS is under 0.1 through couous Core Web Vitals optimization.
• Security First: Ensure full HTTPS support with clean, direct HTTP to HTTPS redirects using a thorough HTTPS security validation.
• Implement Structured Data: Use JSON-LD structured data markup for all key content to make it digestible for LLMs. This is a critical step for modern Schema.org LLM markup.
• Fix Crawlability Issues: Eliminate all 3xx redirect chains and fix broken links (404 errors). This is part of implementing AI-friendly crawlability fixes.
• Strengthen Internal Linking: Aim for more than a single internal link per page, creating a rich, context-aware navigation structure.
• Optimize Images: Compress all images and add descriptive alt text. This is a key part of Image alt-text optimization.
• Validate Hreflang: Double-check your hreflang tags across all multilingual content.
• Maintain Redirect Hygiene: Implement a strategy of regular 404 redirect hygiene to prevent user and bot confusion.
• Boost Global Performance: Leverage a CDN global performance boost for international audiences.

Think of your website as a physical body. If the structure (bones), speed (heart rate), and signals (nerves) aren't working correctly, it won’t function well—no matter how beautiful the surface (design) is. In 2025, technical SEO is the fundamental support system for everything your site does, from Google rankings to LLM integrations. It's not just about fixing errors; it's about enabling machines and people to understand your content better, faster, and in more places.

If your site is struggling to rank, don't just throw more content at the problem. Start by checking the foundation. A strong technical SEO strategy, with an eye toward LLM readiness, is the most impactful investment you can make for your site’s future.