Technical SEO
Technical SEO covers the infrastructure that lets search engines crawl, render and index a site reliably: correct HTTP status codes and redirects, a fast and mobile-friendly experience, HTTPS, JavaScript that renders the important content, sensible URL structures, international targeting and valid structured data.
Which status codes matter?
| Code | Meaning for Google |
|---|---|
| 200 | Content can be considered for indexing |
| 301 / 308 | Permanent redirect: a strong signal that the target is canonical[1] |
| 302 / 307 | Temporary redirect: a weak canonical signal[1] |
| 404 / 410 | Page not found or gone; drops out of the index over time[2] |
| 429, 5xx | Google temporarily slows crawling; prolonged errors can lead to removal[2] |
What is page experience?
Google’s page experience guidance covers Core Web Vitals, HTTPS, mobile usability and avoiding intrusive interstitials.[3] Core Web Vitals measure loading (Largest Contentful Paint, good at 2.5 seconds or less), interactivity (Interaction to Next Paint, good at 200 milliseconds or less) and visual stability (Cumulative Layout Shift, good at 0.1 or less).[4] Officially documented Google says good Core Web Vitals scores alone do not guarantee top rankings.[3]
How does JavaScript affect SEO?
Google processes JavaScript in three phases (crawling, rendering and indexing) and can render most modern pages, but rendering can be delayed and some patterns fail.[5] Officially documented Structured data can be generated with JavaScript and Google can read it after rendering,[6] but many other crawlers do not run JavaScript, so server-rendered HTML and JSON-LD are the safer choice. Practitioner practice
What else belongs in a technical audit?
- HTTPS everywhere, with HTTP and
wwwvariants redirecting to one host. - Mobile-first parity: the same content and structured data on mobile and desktop.[7]
- Readable URL structure.[8]
hreflangfor language or regional versions.[9]- Valid structured data, tested with the Rich Results Test and the Schema Markup Validator.[10][11]
- A WebSite
nameon the homepage so Google can show your site name.[12]
Why does technical SEO matter for entities and AEO?
Your structured data and facts are only useful if crawlers can fetch and parse them. Answer engines add their own crawlers and rendering limits; see AEO.wiki on rendering, speed and access and the SEO to AEO page here.
Frequently asked questions
Is a 301 or 308 redirect better?
Google treats both as permanent redirects. Use whichever your server supports; 308 preserves the request method.
Do Core Web Vitals decide rankings?
They are part of page experience, but Google says good Core Web Vitals scores do not guarantee top rankings and that it seeks to show the most relevant content.
Can Google read JSON-LD added with JavaScript?
Yes, after rendering, according to Google. Other crawlers may not render JavaScript, so server-side output is safer.
See also
References
Pages accessed September 29, 2026 unless a date is given. See all sources and our editorial policy.
- ^ "Redirects and Google Search". Google Search Central.
- ^ "How HTTP status codes, and network and DNS errors affect Google Search". Google Search Central.
- ^ "Understanding page experience in Google Search results". Google Search Central.
- ^ "Web Vitals". web.dev (Google Chrome team).
- ^ "Understand JavaScript SEO basics". Google Search Central.
- ^ "Generate structured data with JavaScript". Google Search Central.
- ^ "Mobile site and mobile-first indexing best practices". Google Search Central.
- ^ "URL structure best practices for Google Search". Google Search Central.
- ^ "Tell Google about localized versions of your page". Google Search Central.
- ^ "Rich Results Test". Google Search.
- ^ "Schema Markup Validator". Schema.org.
- ^ "Provide a site name to Google Search". Google Search Central.