Adminer is a full-featured MySQL management tool written in PHP. This plugin include this tool in WordPress.

Google analytics counter tracker - analyse the visitors hits on you website and display it graphically

The Plugin Debug Objects provides a large number of information: query, cache, cron, constants, hooks, functions and many more.

Un plugin de statistiques avancées pour WooCommerce permettant d'afficher diverses données sur les commandes, les clients, et les produits.

Use Firebug with FirePHP to analyze the SQL queries made by Wordpress. Ideal for development and avoid performance issues.