Injecting PHP-Code into WordPress posts

Hi,

is there a possibility for injecting php-code into wordpress-posts? Some plugin or something?

I have some plugins I use and in order to make them display something, you need to hardcode the command into the template.

I am now trying to figure out a simpler way to inject the php-code, so I don’t need to edit every new template I choose for my blogs.

Any suggestions?