You can have the best content in your industry, but if Google can't properly crawl and understand your website, it won't rank. That's what technical SEO is all about, and why choosing the right technical SEO agency matters so much.
In this guide I'll explain what technical SEO covers, why it's more important than ever, what services the best agencies provide, and how to choose and work with one. Technical SEO is a core part of our SEO services, so I'll share how we approach it too.
What Is Technical SEO?
Technical SEO is the work that makes sure search engines can find, crawl, render and index your website efficiently. It's the foundation everything else sits on. Content and links can only do their job if the technical basics are right.
Think of it this way: on-page SEO is what's in the shop window, off-page SEO is your reputation on the high street, and technical SEO is whether the shop door opens at all.
What Is Included in Technical SEO?
A thorough technical SEO service typically covers:
- Crawlability and indexing: making sure Google can reach and index the pages that matter, and ignores the ones that don't
- Site speed and Core Web Vitals: how quickly your pages load and respond
- Mobile-friendliness: Google primarily uses the mobile version of your site for ranking
- Site structure: a logical hierarchy and internal linking that help users and search engines navigate
- XML sitemaps and robots.txt: guiding search engines to your important content
- Redirects and broken links: fixing 404s, redirect chains and loops
- Duplicate content: canonical tags and handling URL variations
- Structured data: schema markup that helps Google understand your content and can earn rich results
- HTTPS and security
- JavaScript rendering: making sure content loaded by JavaScript is visible to search engines
- Site migrations: protecting rankings when you redesign or move your website
Why Is Technical SEO So Important?
Google has to see your content before it can rank it
If key pages aren't indexed, they won't appear in search results at all, however good they are.
Speed affects rankings and sales
Slow websites frustrate users, increase bounce rates and lose sales. Page experience is also part of how Google evaluates websites.
Modern websites create new problems
Many websites, particularly those built with JavaScript frameworks or AI website builders, load content in ways search engines can struggle with. I've seen AI-built sites where Google indexed almost nothing until the rendering was fixed. Does Google crawl JavaScript? It can, but not always reliably or quickly. That's why technical expertise matters more than ever.
AI search relies on clean, structured sites
AI overviews and AI assistants draw on websites they can easily access and understand. Clean structure and schema help your content get picked up.
Warning sign: if you've recently launched a new website and your traffic dropped, a technical SEO issue is the most likely cause.
What Services Do the Best Technical SEO Agencies Provide?
The best technical SEO agencies go beyond running a crawler and sending you a spreadsheet. Look for:
- In-depth technical audits with prioritised, plain-English recommendations. See what an SEO audit includes.
- Implementation, not just advice. Can they fix the issues, or work directly with your developer?
- Site migration support to protect rankings during redesigns.
- Speed optimisation covering images, code, caching and hosting.
- Schema markup implementation.
- Ongoing monitoring so new issues are caught early.
- Web development knowledge. Agencies that also build websites understand how technical fixes are implemented.
How to Choose the Right Technical SEO Agency
1. Check they can explain technical issues simply
If an agency can't explain what's wrong in plain English, they'll struggle to help you prioritise. Technical expertise should come with clear communication.
2. Ask whether they implement fixes
Some agencies only diagnose. That's fine if you have a strong in-house developer. If you don't, you need an agency that can make the changes.
3. Look for experience with your platform
WordPress, Shopify and custom-built or AI-generated sites each have their own technical quirks. Ask about their experience with your setup.
4. Ask about migrations
If you're planning a redesign, ask how they'd protect your rankings. A good answer covers redirect mapping, pre-launch testing and post-launch monitoring.
5. Ask how they prioritise
Every website has technical issues. The skill is knowing which ones actually affect rankings and revenue. Ask how they decide what to fix first.
6. Check their results
Look for case studies and genuine reviews that mention speed, rankings and visibility improvements.
How to Work With a Technical SEO Agency
To get the best from a technical SEO agency:
- Give them the right access: Google Search Console, Google Analytics, your CMS and hosting where needed.
- Connect them with your developer if you have one, so fixes can be implemented quickly.
- Agree priorities together. Focus first on issues that affect your most valuable pages.
- Involve them early in any redesign. It's far cheaper to build SEO in than to fix it after launch.
- Keep communication open. Let them know about planned changes to your website.
How SERPentity Approaches Technical SEO
We're both a web design and an SEO agency, so we understand technical SEO from the build up. We don't just identify issues, we fix them. That includes speed optimisation, schema markup, site structure and indexing problems.
Speed and technical quality are recurring themes in our client reviews. REYTFEST's site handled busy traffic without slowing down, and Twelve Trees Care highlighted how quickly their site loads. If you need a new site built with technical SEO baked in, see our web design service.
Technical SEO Issues We See Most Often
To give you an idea of what a technical SEO agency actually fixes, these are the issues we come across most:
- Pages accidentally set to "noindex", often left over from a development site
- Content hidden behind JavaScript that search engines can't render properly
- Missing redirects after a redesign, sending old URLs and their rankings to 404 pages
- Oversized images slowing mobile load times
- Duplicate pages caused by URL parameters, trailing slashes or http/https versions
- Orphan pages with no internal links pointing to them
- Incorrect canonical tags telling Google to ignore the wrong pages
- Missing or broken schema markup
Each of these can quietly hold back an otherwise good website. Fixing them often produces some of the fastest improvements in any SEO campaign.
Technical SEO for Websites Built With AI Tools
AI website builders and "vibe coding" platforms make it faster than ever to launch a website. But speed of build doesn't guarantee search visibility. Many of these tools produce JavaScript-heavy sites with missing metadata, no sitemap, weak heading structure and no schema markup.
If you've built a site this way and it isn't appearing on Google, the fix usually involves server-side or pre-rendering so search engines can see the content, adding proper titles, meta descriptions and canonical tags, generating an XML sitemap, and adding structured data. These are exactly the kinds of fixes a technical SEO agency handles. We work with modern and AI-built sites regularly, so we know where the common problems hide.
Whatever platform your site runs on, the principle is the same: if Google can't read it, it can't rank it.
Final Thoughts
Technical SEO isn't glamorous, but it's the foundation of every successful SEO campaign. The right agency will find what's holding your site back, explain it clearly and fix it, so your content and links can deliver their full value.
Want to know if technical issues are holding your site back? Get a free SEO audit and we'll check.
