Although b2evolution uses PHP, PHP is not a part of b2evolution, so do you mean this list :: http://php.net/manual/en/extensions.php?
or
for Microsoft Windows do you want things like https://mlocati.github.io/articles/php-windows-imagick.html
and then there is
https://support.plesk.com/hc/en-us/articles/115003511013-How-to-install-GraphicsMagick-gmagick-PHP-extension-

That's not my question. What are the technical specifications and extensions (PHP) required for B2 in server

https://b2evolution.net/man/system-requirements

Yes,

I have read that but not answer.

Just been investigating your request, not directly with b2evo. Although a bit dated you would like to try this as a starter
http://php5.laurent-laville.org/compatinfo/ as mentioned at
https://wordpress.stackexchange.com/questions/42098/what-are-php-extensions-and-libraries-wp-needs-and-or-uses

I'm now wondering why you want to know :=)

These are the ones I use on 7.2 for v6.10.7 :: though they are pretty much a default set

So to find the minimum you disable one at a time and see if you get errors. Might try it myself for fun :)

@nospy

I have read that but not answer.

You need me to copy/paste ?

• It is highly recommended that the "mbstrings" extension is installed. (Not a problem with most web hosts)
• Graphics related functions require the PHP GD module. (Not a problem with most web hosts)
• XML-RPC related functions and XHTML validation require the PHP XML Reader module. (Not a problem with most web hosts)
• For best performance it is also recommended to use caching. In PHP 7 we recommend to enable APCu.

Additionally, the system status page will tell you if you have an important module missing -- https://b2evolution.net/man/system-status-tab/