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WP-Debug Screenshot
WP-Debug Screenshot
WebDevStudio has created WP-Devel which uses the foundation of WP-Debug and has added enhancements. I’m no longer updating WP-Debug but instead pointing to their work.

I was using my StumbleUpon, and I came across Krumo which is a PHP debugging application. It allows you to see the content of server variables, cookies, and a lot more including specified variables such as $wp_query! After a short while I had a running WordPress plugin which should be an asset for WordPress developers.


  1. Download, upload, activate.

That’s it! As long as you’re logged in you’ll see the expandable menus in the footer of your page (nothing is shown to your visitors). It does rely on having the wp_footer() call in your theme so ensure that’s there if you don’t see anything.


Krumo comes with some default styles: default, blue, green, orange, and It is set to default which works the best with the default WordPress theme. If you would like to change it you can go to the “krumo” folder of the plugin and edit the “selected” value in the krumo.ini file (you might have to adjust the styles depending on how CSS inheritance from your theme throws things off).

selected = "default"

I have most of the Krumo API in the plugin, but you can add/remove at your lesiure. If you want to check a variable then simply add to lines 14, but you can see on line 14 that I had to declare WordPress variables as global, because the content is outside the loop. Simply add a global variable to line 12 if needed.

global $user_ID, $wp_query, $wp;
if ( $user_ID ) {
include ('krumo/class.krumo.php');

Be sure to check the documentation for their API if need be.


  1. Hi There Chris –
    This looks at a great plug-in… thank you very much. I recently ran into some slow-loading page issues for my WordPress websites and tried a bunch of things to address the issue(s) (see forum post at

    I plan to blog about your plugin at Do you have a donation button for your plugin?
    – Scott

  2. @Scott: I’m glad you liked it, and thanks for the publicity. I added a donation button above, and I also have a link for it.

  3. GM

    Activated version wp-debug 1.0 on WP2.3.1, and get the following error at the bottom of pages.

    Fatal error: Call to undefined function: getallheaders() in /wp-content/plugins/wp-debug/krumo/class.krumo.php on line 260

    Still digging into it, but curious if you have heard of others running into this.

  4. @GM: If you comment that particular function on line 26 of wp-debug.php do you get any other errors? I’m guessing it’s associated with your server.

  5. GM

    Commenting out line 26 worked. What functionality am I missing with it removed?

  6. @GM: You’ll won’t get the PHP header information (what browser you are using, etc). Not critical.

  7. Hi Chris,

    thanks for the great plugin. I was always looking for such structured information for debugging purposes.

    I did some modifications to the plugin code and also to the krumo class itself. If you are interested in this code, I would be happy to share this.

    I did the following changes:
    – Krumo output is now also displayed on the admin pages of WordPress
    – A developer can call the debug functions itself. In this case it is assumed that she would like only to see the requested information. The predefined bunch of krumo calls are skipped in this case
    – If a developer calls the debug function itself, the output will also go to the footer of the page
    – Krumos recursion detection wasn’t acutally a recursion detection but a reference detection. This lead to more recursion warnings as necessary

  8. @Soren: I just sent you an e-mail. Please do share.

  9. Hello Chris,

    I am looking for a way to do debug output during ajax calls. Would your plugin allow that?

  10. Thanks Chris

    Do you know of a way to call firebug’s console.log from a php function?

  11. @Vladimir: Not with PHP that I know of. You can try FirePHP, but I’ve never gotten it to work.

  12. I am puzzling with idea to make a debug plugin that will allow real time debuging from anywhere.

    you would open a new browser window and point it to a debug server which will receive information from your plugin or whatever in realtime. Have time for that? :)

  13. @Vladimir: Sorry, I don’t have any interest. I will however be releasing a new version of WP-Debug soon, but it still won’t address your needs.

  14. Hi, I accidentally installed this on my PHP4 hosting service and found nothing in my WP install worked. All failing looking for the debug_print_backtrace() function. In your btev.php module you call this twice, but you only check for it’s existence in the first one. Fixing it was a simple matter of copying the code block from the first call (lines 1054-1065) over the second call (from line 1108).

  15. @David: What line is this in? Is it in the Krumo class?

  16. David Edwards

    My apologies, it’s in btev.php which is part of the bluetrait event viewer plugin, not yours.

  17. Brett

    Running WordPress 2.9.2, I downloaded, uploaded and activated and nothing shows up… anywhere. I checked the page source, I checked the footer and nothing is showing, not even an error.

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