Adds an interactive PHP console (REPL) to the WordPress admin. You can run arbitrary PHP code and access any function, class or variable defined by WordPress or active plugins. Amazing for debugging and exploration.
Note: At the time of this writing, the plugin directory listing says this plugin is only “compatible up to 3.3.2”, but in practice it works fine even with WP 3.5 beta. Tested it myself.
Helps you set up your development environment by making it extremely easy to install a number of recommended debugging and development plugins. For example, you can install and activate the excellent Debug Bar plugin (see below) with a single click.
Adds a “Debug” menu to the WordPress toolbar that displays executed SQL queries, WP query information and object cache statistics. There’s a number of great debugging plugins that extend Debug Bar with additional features, some of which you’ll find listed below.
Adds information about transients to the Debug Bar. This plugin will display all transients grouped by type (i.e. custom, core, network-wide, etc) along with their values and expiration times. You can also easily delete a transient.
Adds a PHP/MySQL console to the Debug Bar. Has a nice, clean interface and supports syntax highlighting. Any code you enter in the console will execute in the WordPress environment, so you can freely use any functions and classes defined in WP or active plugins.
However, unlike with the WordPress Console plugin mentioned above, you’ll need to explicitly declare global variables as
global $var; to be able to use them, and new variables you create won’t be preserved between requests.
Displays a list of hooks executed on the current page in the Debug Bar. Nice and simple.
Lets you dump variables and backtraces in a nicely styled, collapsible format. Basically, whenever you would use
var_dump(), use the
d() function provided by this plugin instead, and your debug output will instantly become much easier to read. All variables and traces are displayed in a new panel in the Debug Bar so that you can find them all in one place.
Displays a huge amount of debugging information in the page footer. This includes the PHP/MySQL/WP version, PHP configuration flags, WordPress cookies, filesystem information, superglobals like $SERVER and $COOKIE, all registered hooks, object cache stats, queued scripts and styles, Cron events, and much more.
This short and simple plugin displays the name of the current template file in the WP Toolbar (a.k.a Admin Bar).
Lets you test and tweak various aspects of the WordPress core including the filesystem, HTTP, Cron, and plugin, theme and core updates. For example, it can list cron jobs, display the available HTTP transports and HTTP-related filters and constants, disable specific transports, log all outgoing HTTP requests, enable/disable filesystem APIs, force update checks, and more. All in all, this is a very powerful debugging tool.
Note: Though the plugin hasn’t been updated in a while, it works just fine with the latest version of WordPress.
Displays a stack trace for every PHP error triggered by WordPress or a plugin/theme. This can be useful in situations where you need to find out what caused an error but don’t have enough access to install Xdebug on the server (e.g. client sites).
Alternative: Simple Error Handler
And A Few More…
- Rewrite Rules Inspector – list and analyze rewrite rules.
- WP-FirePHP – dump variables to Firebug.
- AskApache Debug Viewer – powerful, similar to Debug Objects (see above), but was a little unstable in my tests.
- Error Log Monitor – displays recent PHP errors in a Dashboard widget, sends email notifications.