What is technical SEO?
Technical SEO is the practice of making a website easy for search engines and AI crawlers to crawl, render, understand and trust. It covers everything below the surface of content and links: how a site is structured, how fast it loads, how its pages are marked up, and whether automated systems — Google, Bing, and now ChatGPT, Claude and Perplexity — can read it cleanly.
Think of it as the foundation. You can write the best page in your category, but if a crawler can’t reach it, render it, or parse what it means, it won’t rank and it won’t be cited. A technical SEO agency’s job is to remove every obstacle between your content and the systems that decide who gets surfaced.
What a technical SEO agency actually covers
Crawlability & indexation
Robots directives, XML sitemaps, canonical tags, crawl-budget management, and fixing the duplicate, orphaned or accidentally no-indexed pages that quietly cap a site’s ceiling.
Site architecture & internal linking
A logical hierarchy of pillar and supporting pages, with internal links that pass authority to the pages that convert. Good architecture is also what lets a model understand how your topics relate.
Core Web Vitals & performance
Largest Contentful Paint, Interaction to Next Paint, Cumulative Layout Shift — plus the rendering and JavaScript issues behind them. Speed is both a ranking signal and a conversion lever.
Structured data (schema)
JSON-LD for Organization, Article, FAQPage, Product, BreadcrumbList and more. Schema is how you tell machines what a page means, not just what it says — and it directly improves eligibility for rich results and AI citations.
AI-crawler readiness (the new layer)
Whether GPTBot, ClaudeBot, PerplexityBot and Google-Extended can access and parse your pages; a clean llms.txt and content-summary layer; and instrumentation to see which AI bots crawl which pages, how often. This is the discipline most legacy agencies don’t yet offer. See how it fits the wider B2B SEO brief.
How AI crawlers change technical SEO in 2026
For twenty years, “can Googlebot read this?” was the central technical question. Now there are five crawlers that matter, and the AI ones behave differently: they re-crawl frequently, they prefer clean server-rendered HTML over heavy JavaScript, and they reward content structured as direct answers, definitions and FAQs.
- Render simply. Content that only appears after client-side JavaScript is often invisible to AI crawlers. Server-render the substance.
- Structure for lifting. A direct-answer sentence near the top, clean headings, definition lists and FAQ blocks make it trivial for a model to quote you accurately.
- Mark it up. Schema and an
llms.txtsummary remove ambiguity about what your page is and who it’s for. - Measure it. If you can’t see which AI bots crawl which pages, you’re flying blind on half of search.
What’s in a good technical SEO audit
An audit is the usual starting point. A strong one is diagnostic and prioritised — not a 90-page export of every warning a tool can generate.
- Crawl & index health: what’s indexed vs what should be, orphan pages, duplicate content, canonical errors.
- Performance: Core Web Vitals by template, the specific causes, and the fixes ranked by impact.
- Architecture & internal links: where authority pools and where it leaks.
- Structured data: what schema exists, what’s missing, what’s invalid.
- AI-crawler readiness: render checks,
llms.txt, and AI-bot crawl logs. - A prioritised roadmap: the few fixes that move the needle, sequenced — and an owner for each.
You can see a lightweight version of this instantly with the free Bloxx audit — it scores any URL on the same checks and shows how AI tools currently read it.
How much does a technical SEO agency cost?
A one-off technical audit typically costs £1,500–£8,000; ongoing technical retainers start around £1,500/month and rise with site size and release cadence.
| Engagement | Typical price | Best for |
|---|---|---|
| One-off audit | £1.5k–£8k | Diagnosing a plateau or pre-migration |
| Audit + implementation | £5k–£20k project | Fixing a backlog of technical debt |
| Technical retainer | £1.5k–£6k/mo | Large or fast-shipping sites |
| Platform (Bloxx) | built in | Pages that ship technically correct by default |
How to choose a technical SEO agency
- They diagnose, then prioritise. The value is in knowing which three fixes matter, not in listing 300.
- They can ship, or work with those who can. Recommendations that never reach production are worthless.
- They understand rendering. JavaScript, server-rendering and how crawlers actually see your pages.
- They cover AI crawlers. Ask to see your AI-bot crawl logs and
llms.txtstatus. - They measure outcomes. Indexation, Core Web Vitals, rankings and citations — before and after.
Where Bloxx fits
Most technical SEO debt comes from the CMS: pages that ship without schema, with messy markup, slow templates or no AI-crawler instrumentation. Bloxx removes the debt at the source. Every page it publishes passes a 25-point technical pass before going live — schema, semantic HTML, clean heading hierarchy, canonical, sitemap, llms.txt, Core Web Vitals baseline and ARIA — and the dashboard shows per-bot crawl logs across Google and the AI engines.
If you’d rather not relitigate technical SEO every time you ship a page, that’s the point of building on Bloxx. Run the free audit to see how a page scores today.
Frequently asked questions
What does a technical SEO agency do?
A technical SEO agency makes a website easy for search engines and AI crawlers to crawl, render, understand and trust. That includes crawlability and indexation, site architecture, Core Web Vitals and page speed, structured data (schema), internal linking, and — increasingly — AI-crawler readiness so engines like ChatGPT and Perplexity can read and cite your pages.
How much does technical SEO cost?
A one-off technical audit typically costs £1,500–£8,000. Audit-plus-implementation projects run £5,000–£20,000, and ongoing technical retainers start around £1,500/month, scaling with site size and how often you ship. A platform that enforces technical correctness on every page (like Bloxx) folds much of this into the build itself.
Is technical SEO still relevant with AI search?
More than ever. AI crawlers like GPTBot, ClaudeBot and PerplexityBot prefer clean, server-rendered HTML with clear structure and schema. The same technical work that helps Googlebot now also determines whether AI answers can read and cite you — so technical SEO has gained a whole new surface, not lost relevance.
What is the difference between technical SEO and on-page SEO?
Technical SEO concerns how a site is built and served — crawlability, speed, architecture, markup. On-page SEO concerns the content of individual pages — titles, headings, copy and keyword targeting. They overlap (schema and internal linking sit between them) and both are needed; technical SEO is the foundation on-page work sits on.
How long does technical SEO take to show results?
Fixes to indexation or rendering can show within days to a few weeks as crawlers re-process your pages. Performance and architecture improvements usually compound over 1–3 months. AI-crawler readiness can move quickly because those bots re-crawl frequently.