Technical SEO for JavaScript and React sites

Technical SEO audits

An audit starts with what a search engine actually receives: the HTML before any script runs, each page’s title, description and canonical address, its structured data, the sitemaps, and which pages Google Search Console and Bing Webmaster Tools say are indexed. You get a written report with each problem, its fix and the order to fix them in, starting with what costs you the most.

SEO for React, Next.js and single-page apps

A single-page app often sends every address the same empty page and builds the content with JavaScript. Some crawlers wait for it; many do not. The fix depends on the stack: server-side rendering (Ahjez’s website is server-rendered with Next.js), pages pre-rendered ahead of time (WonderTech’s catalogue), or, when the framework stays, a readable HTML page written for every address at build time. That last one is how this portfolio, a WebGL scene, is read in full by search engines and language models.

Programmatic SEO: pages from your data

Programmatic SEO publishes one useful page for each thing people search for, generated from data you already have. Calculi turned the national orientation guide, a 203-page PDF whose score tables were images, into 3,215 programmes and 870+ pages, with a page for each of 709 programme codes, every one searchable in French and Arabic and listed in a generated sitemap with its structured data. The whole guide ships as 47 KB of compressed data, so its pages load fast.

Thin pages pull a whole site down, so they are kept out of the index: on Calculi’s two publications, robots rules stop pages with nothing to say from being offered to search engines.

Visibility in AI answers

Assistants such as ChatGPT and Perplexity quote pages they can read and understand. The same groundwork helps them: text that exists without scripts, structured data that says who and what a page is about, and a short map of the site written for language models (llms.txt). This site has all three.

Speed and Core Web Vitals

Speed counts in ranking and in keeping a visitor. Invariant has a measured layout shift of 0.00; WonderTech’s pages are pre-rendered and served from cache; Calculi stays fast on the phones 78% of its users read it on.

Multilingual and international SEO

A site in two languages needs each language to be a page of its own, with its own address, rather than text swapped by a script. Calculi’s interface is French and its data Arabic, with one search box across both and share cards in each interface language, and its two publications each keep their own sitemaps and structured data.

Prices

Clients in Tunisia (TND)

Europe (EUR)

Rest of the world (USD)

Prices for clients in Tunisia, clients in Europe, clients outside Tunisia and Europe. Each range is where most projects of that kind land; you get a written quote after a first call about what you need. Domains, hosting, paid services and store fees are paid to their providers, in your name.

Proof

• Calculi: 870+ pages generated from a 203-page PDF; 80% of visits from organic search.
• This Portfolio: A WebGL site with a readable page, structured data and a sitemap entry for every address.
• Calculi Blog & Invariant: Two publications with their own sitemaps and structured data, and a layout shift of 0.00.
• WonderTech: Pre-rendered catalogue pages, each with its own metadata and structured data.

Questions

How much does SEO cost?

A technical SEO audit is 300 – 880 TND for clients in Tunisia, €200 – €500 in Europe and $230 – $550 elsewhere. A programmatic SEO build, from your data to published pages, is 2,000 – 6,250 TND for clients in Tunisia, €1,250 – €3,750 in Europe and $1,400 – $4,150 elsewhere. Ongoing work is billed by the day: 130 – 200 TND a day for clients in Tunisia, €80 – €110 a day in Europe and $80 – $120 a day elsewhere.

Is React bad for SEO?

Not by itself. The problem is a React app that sends search engines an empty page. Server-side rendering, pre-rendering or a static page for every address fixes it without giving up React: this site is built with React and serves every address as readable HTML.

What is programmatic SEO?

Publishing many pages from structured data, one for each thing people search for: a product, a city, a job, a study programme. It works when each page is useful on its own. Each of Calculi’s 870+ guide pages answers a question students actually type.

How long until SEO shows results?

Weeks for fixes to be crawled, months for rankings to move, and longer for a new site. Calculi grew year on year: four times as many users in 2024 as in 2023, and twice as many again in 2025, without ever buying an ad.

Tell me about your project

Say what it is for, what you have already and by when. I reply with my questions, or with a time for a first call.

• Email: [email protected]
• Phone: +(216) 44 674 320