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Laravel Debugbar (Integrates PHP Debug Bar)
The Debug component provides tools to ease debugging PHP code.
PHP errors for cool kids
Debug bar for PHP
The DebugBundle allows greater integration of the VarDumper component in the Symfony full-stack framework.
The VarDumper component provides mechanisms for walking through any arbitrary PHP variable. It provides a better dump() function that you can use instead of var_dump().
Xdebug — Step Debugger and Debugging Aid for PHP
Clockwork - php dev tools integrated to your browser - server-side component