The essentials
- Definition: URL rewriting maps a readable address (
/seo/audit-seo/) to a technical one (index.php?cat=3&id=127) on the server side, with no visible redirect. - The SEO effect: modest on direct ranking, real on click-through rate, understanding by Google and by people, sharing and maintenance.
- The rules: short, lower case, words separated by hyphens, no unnecessary parameters, stable over time, one URL per piece of content.
- The real risk: changing URLs without 301 redirects during a redesign.
TheURL rewriting, or URL rewriting, is a web server mechanism that lets you show readable addresses in place of the technical ones an application generates. The user and Google see /seo/audit-seo-complet/ ; the server actually runs index.php?section=seo&article=127. Every modern CMS does it by default; it is still worth understanding what it brings to SEO, how to write a good URL and how to avoid damage during a migration.
How it works
The server (Apache, Nginx, IIS) or the application applies rules translating the requested URL into the internal resource. The translation is transparent: no redirect, and the response code stays 200. Examples:
| Server | Rule (extract) | Effect |
|---|---|---|
| Apache (.htaccess) | RewriteRule ^produit/([a-z0-9-]+)/?$ produit.php?slug=$1 [L] | /produit/chaise-bois/ serves produit.php?slug=chaise-bois |
| Nginx | rewrite ^/produit/([a-z0-9-]+)/?$ /produit.php?slug=$1 last; | The same behaviour |
| A CMS (WordPress, Shopify, Prestashop) | The permalinks setting | Rewriting handled without touching the server |
Don't confuse rewriting with redirection: rewriting changes what the server runs without changing the address shown; a redirect (301 or 302) sends the browser to another address. The codes are detailed in HTTP response codes.
What URL rewriting brings to SEO
- Readability and click-through rate: a URL describing the content reassures people in the results and in shares; Google sometimes shows it as a breadcrumb.
- Understanding: the words in the URL are a light relevance signal, confirmed by Google as minor but real.
- Structure: hierarchical URLs (
/seo/audit-seo-complet/) reflect the site's structure, which helps internal linking and analysis (Search Console, GA4 by directory). - Crawling: URLs with no parameters avoid duplicates (
?id=127&sort=ascand?sort=asc&id=127are two URLs to Google) and save crawl budget; see duplicate content. - Stability: a URL decoupled from the technology survives a change of CMS, if you keep it.
The direct effect on ranking is small: a page with a technical URL but good content will rank. Rewriting is hygiene, not a growth lever.
Writing a good URL
| Rule | Good example | To avoid |
|---|---|---|
| Short, 3 to 5 useful words | /seo/audit-seo-complet/ | /seo/comment-realiser-un-audit-seo-complet-de-votre-site-en-2026/ |
| Lower case, no accents, hyphens | /referencement-local/ | /Référencement_Local/ |
| No stop words and no dates | /choisir-prestataire-seo/ | /comment-choisir-son-prestataire-seo-en-2024/ |
| A hierarchy limited to 2 or 3 levels | /outils/google-search-console/ | /ressources/articles/outils/google/search-console/ |
| No parameters for the content | /produit/chaise-bois/ | /produit.php?id=127&ref=abc |
| One canonical form only | With a trailing slash, on HTTPS, without www or with, but only one | Four variants all returning 200 |
| Stable | The URL contains neither a shifting category nor a date | /2024/03/promo/article/ |
Parameters remain legitimate for functions (sorting, filters, pagination, UTM tracking); they should then be handled by a canonical tag pointing to the main URL.
Redesign and migration: the real issue
Most traffic losses after a redesign come from URLs changed with no redirect. Every old URL that was indexed or linked must respond with a 301 to its exact equivalent, not to the home page. The method: export every existing URL (a crawl, Search Console, GA4, a backlink tool), build the old → new mapping table, implement the 301s, test before going live, then watch the 404s in Search Console for three months. A crawler such as Screaming Frog checks the whole thing in minutes. If the current URLs are fine, the best decision is not to change them.
Checking your site
- Crawl the site and list the URLs with parameters, capitals, accents or more than 100 characters.
- Check each piece of content is reachable through only one URL (the others redirect or carry a canonical).
- Check the Pages report in Search Console: "duplicate without user-selected canonical" and "crawled, currently not indexed" URLs often signal a parameter problem.
- Fold these checks into the full SEO audit.
How GreenRed helps
Rather than juggling several tools, GreenRed's Site health module brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
Does URL rewriting improve Google ranking?
Weakly. Google has confirmed the words in the URL are a minor signal. The real benefits are click-through rate, the absence of parameter-related duplicates, readability for people and a usable site structure. No site climbs ten places thanks to its URLs.
Should you put keywords in URLs?
The page's main word, yes, because it describes the content. But no repetition and no stacking: a URL of 3 to 5 useful words, echoing the title's subject, is enough. Keyword stuffing in the URL adds nothing and harms readability.
Should you change existing technical URLs?
Only if they cause a real problem (duplicates, uncontrolled parameters) or during a CMS migration, and always with 301 redirects one by one. A technical but stable and indexed URL beats a clean URL that has lost its links.
Trailing slash or not, www or not: does it matter?
The choice doesn't matter, the consistency does. Decide on one form (HTTPS, no www, with a trailing slash, for example) and redirect every other to it. Otherwise Google sees several versions of each page and scatters the signals.