Getting Started with Tracy

Tracy library is a useful helper for everyday PHP programmers. It helps you to:

  • quickly detect and correct errors
  • log errors
  • dump variables
  • measure execution time of scripts/queries
  • see memory consumption

PHP is a perfect language for making hardly detectable errors because it gives great flexibility to programmers. Tracy\Debugger is more valuable because of that. It is an ultimate tool among the diagnostic ones.

If you are meeting Tracy for the first time, believe me, your life starts to be divided into one before the Tracy and the one with her. Welcome to the good part!

Installation and Requirements

The best way how to install Tracy is to download the latest package or use Composer:

composer require tracy/tracy

Alternatively, you can download the whole package or tracy.phar file.


Tracy is activated by calling the `Tracy\Debugger::enable()' method as soon as possible at the beginning of the program, before any output is sent:

use Tracy\Debugger;

require 'vendor/autoload.php'; // alternatively tracy.phar


The first thing you'll notice on the page is the Tracy Bar in the bottom right corner. If you don't see it, it may mean that Tracy is running in production mode. This is because Tracy is only visible on localhost for security reasons. To test if it works, you can temporarily put it into development mode using the Debugger::enable(Debugger::Development) parameter.

Tracy Bar

The Tracy Bar is a floating panel. It is displayed in the bottom right corner of a page. You can move it using the mouse. It will remember its position after the page reloading.

You can add other useful panels to the Tracy Bar. You can find interesting ones in addons or you can create your own.

If you do not want to show Tracy Bar, set:

Debugger::$showBar = false;

Visualization of Errors and Exceptions

Surely, you know how PHP reports errors: there is something like this in the page source code:

Parse error:  syntax error, unexpected '}' in HomePresenter.php on line 15

or uncaught exception:

Fatal error:  Uncaught Nette\MemberAccessException: Call to undefined method Nette\Application\UI\Form::addTest()? in /sandbox/vendor/nette/utils/src/Utils/ObjectMixin.php:100
Stack trace:
#0 /sandbox/vendor/nette/utils/src/Utils/Object.php(75): Nette\Utils\ObjectMixin::call(Object(Nette\Application\UI\Form), 'addTest', Array)
#1 /sandbox/app/forms/SignFormFactory.php(32): Nette\Object->__call('addTest', Array)
#2 /sandbox/app/presenters/SignPresenter.php(21): App\Forms\SignFormFactory->create()
#3 /sandbox/vendor/nette/component-model/src/ComponentModel/Container.php(181): App\Presenters\SignPresenter->createComponentSignInForm('signInForm')
#4 /sandbox/vendor/nette/component-model/src/ComponentModel/Container.php(139): Nette\ComponentModel\Container->createComponent('signInForm')
#5 /sandbox/temp/cache/latte/15206b353f351f6bfca2c36cc.php(17): Nette\ComponentModel\Co in /sandbox/vendor/nette/utils/src/Utils/ObjectMixin.php on line 100

It is not so easy to navigate through this output. If you enable Tracy, both errors and exceptions are displayed in a completely different form:

The error message literally screams. You can see a part of the source code with the highlighted line where the error occurred. A message clearly explains an error. The entire site is interactive, try it.

And you know what? Fatal errors are captured and displayed in the same way. No need to install any extension (click for live example):

Errors like a typo in a variable name or an attempt to open a nonexistent file generate reports of E_NOTICE or E_WARNING level. These can be easily overlooked and/or can be completely hidden in a web page graphic layout. Let Tracy manage them:

Or they may be displayed like errors:

Debugger::$strictMode = true; // display all errors
Debugger::$strictMode = E_ALL & ~E_DEPRECATED & ~E_USER_DEPRECATED; // all errors except deprecated notices

Note: Tracy when activated changes the error reporting level to E_ALL. If you want to change this, do so after calling enable().

Development vs Production Mode

As you can see, Tracy is quite talkative, which can be appreciated in the development environment, while on the production server it would cause a disaster. That's because no debugging information should be displayed there. Tracy therefore has environment auto-detection and if the example is run on a live server, the error will be logged instead of displayed, and the visitor will only see a user-friendly message:

Production mode suppresses the display of all debugging information sent out using dump(), and of course also all error messages generated by PHP. So if you have forgotten some dump($obj) in the code, you don't have to worry, nothing will be displayed on the production server.

How does mode auto-detection work? The mode is development if the application is running on localhost (i.e., IP address or ::1) and there is no proxy (i.e., its HTTP header). Otherwise, it runs in production mode.

If you want to enable development mode in other cases, for example for developers accessing from a specific IP address, you can specify it as a parameter of the enable() method:

Debugger::enable('23.75.345.200'); // you can also provide an array of IP addresses

We definitely recommend combining the IP address with a cookie. Store a secret token, e.g., secret1234, in the tracy-debug cookie, and in this way, activate the development mode only for developers accessing from a specific IP address who have the mentioned token in the cookie:


You can also directly set the development/production mode using the Debugger::Development or Debugger::Production constants as a parameter of the enable() method.

If you use the Nette Framework, take a look at how to set the mode for it, and it will then also be used for Tracy.

Error Logging

In production mode, Tracy automatically logs all errors and exceptions to a text log. In order for logging to take place, you need to set the absolute path to the log directory to the $logDirectory variable or pass it as the second parameter to enable() method:

Debugger::$logDirectory = __DIR__ . '/log';

Error logging is extremely useful. Imagine that all users of your application are actually beta testers who do top-notch work in finding errors for free, and you would be foolish to throw their valuable reports away unnoticed into the trash bin.

If you need to log your own messages or caught exceptions, use the method log():

Debugger::log('Unexpected error'); // text message

try {
} catch (Exception $e) {
	Debugger::log($e); // log exception
	// or
	Debugger::log($e, Debugger::ERROR); // also sends an email notification

If you want Tracy to log PHP errors like E_NOTICE or E_WARNING with detailed information (HTML report), set Debugger::$logSeverity:

Debugger::$logSeverity = E_NOTICE | E_WARNING;

For a real professional the error log is a crucial source of information and he or she wants to be notified about any new error immediately. Tracy helps him. She is capable of sending an email for every new error record. The variable $email identifies where to send these e-mails:

Debugger::$email = '';

If you use the entire Nette Framework, you can set this and others in the configuration file.

To protect your e-mail box from flood, Tracy sends only one message and creates a file email-sent. When a developer receives the e-mail notification, he checks the log, corrects his application and deletes the email-sent monitoring file. This activates the e-mail sending again.

Opening Files in the Editor

When the error page is displayed, you can click on file names and they will open in your editor with the cursor on the corresponding line. Files can also be created (action create file) or bug fixed in them (action fix it). In order to do this, you need to configure the browser and the system.

Supported PHP Versions

Tracy compatible with PHP
Tracy 2.10 – 3.0 PHP 8.0 – 8.2
Tracy 2.9 PHP 7.2 – 8.2
Tracy 2.8 PHP 7.2 – 8.1
Tracy 2.6 – 2.7 PHP 7.1 – 8.0
Tracy 2.5 PHP 5.4 – 7.4
Tracy 2.4 PHP 5.4 – 7.2

Applies to the latest patch versions.


This is a list of unofficial ports to other frameworks and CMS: