Technical SEO for Next.js and React sites: a practical checklist

A site can be beautiful and fast and still not show up in Google. The cause is usually not the content. It is a technical problem that stops the search engine from seeing or understanding the page. This checklist is what has been applied to this very site.

1. Content in the initial HTML

Crawlers don't always run JavaScript, and some AI crawlers never do. If the main text appears only after a script runs, it doesn't exist for them.

• Use server rendering or static generation.
• Check with "view page source" that the main text is in the first response.
• Don't lock important content behind a click, infinite scroll or a login.

2. Every page has a unique title and description

• title of about sixty characters, containing the main topic.
• description of about one hundred and fifty characters, an honest summary, not an advert.
• No duplicate titles across pages.

3. Stable URLs and a clear canonical

• Each page has one main address, declared with a canonical tag.
• http/https and www/non-www redirect to one address.
• Filter and tracking parameters must not create new indexable URLs.

4. Sitemap and robots

• sitemap.xml includes every indexable page, with a correct lastmod.
• Point to the sitemap in robots.txt and close private paths.
• Mark the admin area and the API as noindex or disallowed.

5. Multilingual sites: hreflang

For each page that has a translation, declare the alternates and give an x-default. An important point: add hreflang only between translations that actually exist. Pointing at a missing page produces errors.

6. Structured data

Schema.org markup tells a machine what each thing is: a person, an article, an organisation, a question and its answer. The full explanation is in what structured data is.

7. Speed and user experience

Google measures Core Web Vitals as part of page experience:

• Load the main image optimised and with set dimensions.
• Subset fonts and set font-display properly.
• Prevent sudden layout shift.
• Drop unnecessary JavaScript.

8. Internal links

• Every article should link to related pieces and receive links from them.
• Link text should be descriptive, not "click here".
• An important page shouldn't be more than three clicks from the home page.

9. Sharing and images

• og:title, og:description and og:image for every page.
• A 1200×630 image with legible text.
• Descriptive alt text for content images.

10. Check and measure

1. Register and verify the site in Search Console.
2. Submit the sitemap and inspect the important pages.
3. In the Pages report, see what isn't indexed and why.
4. Register with Bing Webmaster as well. Several AI assistants use its index, as I explained in GEO.

The takeaway

Technical SEO means nothing stands between the crawler and your content: complete HTML, stable URLs, unique metadata, a sitemap, correct hreflang, structured data and speed. After that, the work is good content.

If your site or product needs a technical review, talk to me.