In PHP 8 the JSON extension is built-in

Author: javiereguiluz

setup.rst

@@ -18,7 +18,7 @@ Technical Requirements
 Before creating your first Symfony application you must:
 
 * Install PHP 8.0.2 or higher and these PHP extensions (which are installed and
-  enabled by default in most PHP 8 installations): `Ctype`_, `iconv`_, `JSON`_,
+  enabled by default in most PHP 8 installations): `Ctype`_, `iconv`_,
   `PCRE`_, `Session`_, `SimpleXML`_, and `Tokenizer`_;
 * `Install Composer`_, which is used to install PHP packages.
 
@@ -315,7 +315,6 @@ Learn More
 .. _`Contrib recipe repository`: https://github.com/symfony/recipes-contrib
 .. _`Symfony Recipes documentation`: https://github.com/symfony/recipes/blob/master/README.rst
 .. _`iconv`: https://www.php.net/book.iconv
-.. _`JSON`: https://www.php.net/book.json
 .. _`Session`: https://www.php.net/book.session
 .. _`Ctype`: https://www.php.net/book.ctype
 .. _`Tokenizer`: https://www.php.net/book.tokenizer