JavaScript Tracking Client

JavaScript Tracking Client

You can use the JavaScript tracking client to track any application that supports JavaScript: for example websites!

This guide will explain how you can use the JavaScript tracking client to customize the way some of the web analytics data is recorded in Matomo (formerly Piwik).

Finding the Matomo Tracking Code

To use all the features described in this page, you need to use the latest version of the tracking code. To find the tracking code for your website, follow the steps below:

  • log in to Matomo with your admin or Super User account
  • click on the "administration" (cog icon) in the top right menu
  • click on "Tracking Code" in the left menu (under the "Measurables" or "Websites" menu)
  • click on "JavaScript Tracking" section
  • select the website you want to track
  • copy and paste the JavaScript tracking code into your pages, just after the opening <body> tag (or within the <head> section)

The tracking code looks as follows:

<!-- Matomo -->
<script type="text/javascript">
  var _paq = window._paq = window._paq || [];
  (function() {
    var u="//{$MATOMO_URL}/";
    _paq.push(['setTrackerUrl', u+'matomo.php']);
    _paq.push(['setSiteId', {$IDSITE}]);
    var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
    g.type='text/javascript'; g.async=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s);
<!-- End Matomo Code -->

In your tracking code, {$MATOMO_URL} would be replaced by your Matomo URL and {$IDSITE} would be replaced by the idsite of the website you are tracking in Matomo.

This code might look a bit strange to those of you familiar with JavaScript, but that is because it is made to run asynchronously. In other words, browsers will not wait for the matomo.js file to be downloaded in order to show your page.

For asynchronous tracking, configuration and tracking calls are pushed onto the global _paq array for execution, independent of the asynchronous loading of matomo.js. The format is:

_paq.push([ 'API_method_name', parameter_list ]);

You can also push functions to be executed. For example:

var visitor_id;
_paq.push([ function() { visitor_id = this.getVisitorId(); }]);

or for example, to fetch a custom variable (name, value) using the asynchronous code:

_paq.push([ function() { var customVariable = this.getCustomVariable(1); }]);

You can push to the _paq array even after the matomo.js file has been loaded and run.

If your Matomo tracking code doesn't look like this one, you may be using the deprecated version. Older versions still work as expected and will track your visitors, but we highly recommend that you update your pages to use the most recent tracking code.


Supported browsers

The JavaScript tracker runs on all browsers that support the JSON API. This includes IE8 and higher. Click here to see a full list of supported browsers.. If you need to support IE7 and older then you could load a polyfill that makes window.JSON available such as JSON3. This polyfill would need to be loaded before the Matomo JS tracker is loaded.

Known incompatibility issues

  • prototype js library overwrites the browser's JSON API and causes issues for example with custom variables resulting in errors (see #16596). Workarounds are to either remove the prototype JS library or to overwrite the JSON object manually (see above e.g. using JSON3).

JavaScript tracker features

Custom page title

By default Matomo uses the title of the HTML page to track the page title, you can customise it by using the function setDocumentTitle:

_paq.push(['setDocumentTitle', document.title]);

If you track multiple sub-domains in the same website, you may want your page titles to be prefixed by the sub-domain make it easy for you to see the traffic and data for each sub-domain. You can do so simply:

_paq.push(['setDocumentTitle', document.domain + "/" + document.title]);

Advanced users can also dynamically generate the page name, for example, using PHP:

_paq.push(['setDocumentTitle', "<?php echo $myPageTitle ?>"]);

Custom page URL

By default, Matomo uses the URL of the current page as the Page URL in reports. You can customise the page URL to track by using the function setCustomUrl, learn more in the FAQ How do I set a custom URL using the Matomo Javascript tracker?

Manually trigger events

By default, Matomo tracks page views when the JavaScript tracking code loads and executes on each page view.

However, on modern web applications, user interactions do not necessarily involve loading a new page. For example, when users click on a JavaScript link, or when they click on a tab (which triggers a JS event), or when they interact with elements of the user interface, you can still track these interactions with Matomo.

To track any user interaction or click with Matomo, you can manually call the JavaScript function trackEvent(). For example, if you wanted to track a click on a JavaScript menu, you could write:

<a href="#" onclick="_paq.push(['trackEvent', 'Menu', 'Freedom']);">Freedom page</a>

You can learn more about Tracking Events in the user guide.

Manually trigger goal conversions

By default, Goals in Matomo are defined as "matching" parts of the URL (starts with, contains, or regular expression matching). You can also track goals for given page views, downloads, or outlink clicks.

In some situations, you may want to register conversions on other types of actions, for example:

  • when a user submits a form
  • when a user has stayed more than a given amount of time on the page
  • when a user does some interaction in your Flash application
  • when a user has submitted his cart and has done the payment: you can give the Matomo tracking code to the payment website which will then register the conversions in your Matomo database, with the conversion's custom revenue

To trigger a goal conversion:

// logs a conversion for goal 1
_paq.push(['trackGoal', 1]);

You can also register a conversion for this goal with a custom revenue. For example, you can generate the call to trackGoal() dynamically to set the revenue of the transaction:

// logs a conversion for goal 1 with the custom revenue set
_paq.push(['trackGoal', 1, <?php echo $cart->getCartValue(); ?>]);

Find more information about goal tracking in Matomo in the Tracking Goals documentation.

Accurately measure the time spent on each page

By default, when a user visits only one page view during a visit, Matomo will assume that the visitor has spent 0 second on the website. This has a few consequences:

  • when the visitor views only one page view, the "Visit duration" will be 0 second.
  • when the visitor views more than one page, then the last page view of the visit will have a "Time spent on page" of 0 second.

It is possible to configure Matomo so that it accurately measures the time spent in the visit. To better measure time spent in the visit, add to your JavaScript code the following:

// accurately measure the time spent in the visit

Matomo will then send requests to count the actual time spent in the visit, as long as the user is actively viewing the page (i.e. when the tab is active and in focus). The heart beat request is executed when:

  • switching to another browser tab after the current tab was active for at least 15 seconds (can be configured see below).
  • navigating to another page within the same tab.
  • closing the tab.
// Change how long a tab needs to be active to be counted as viewed in seconds/
// Requires a page to be actively viewed for 30 seconds for any heart beat request to be sent.
_paq.push(['enableHeartBeatTimer', 30]);

Note: When testing the heart beat timer, remember to make sure the browser tab has focus and not eg. the developer tools or another panel.

Ecommerce tracking

Matomo allows for advanced and powerful Ecommerce tracking. Check out the Ecommerce Analytics documentation for more information about Ecommerce reports and how to set up Ecommerce tracking.

Internal search tracking

Matomo offers advanced Site Search Analytics feature, letting you track how your visitors use your internal website search engine. By default, Matomo can read URL parameters that will contain the search keyword. However, you can also record the site search keyword manually using the JavaScript function trackSiteSearch(...)

In your website, in standard pages, you would typically have a call to record Page views via matomoTracker.trackPageView(). On your search result page, you would call instead piwikTracker.trackSiteSearch(keyword, category, searchCount) function to record the internal search request. Note: the 'keyword' parameter is required, but category and searchCount are optional.

    // Search keyword searched for
    // Search category selected in your search engine. If you do not need this, set to false
    "Organic Food",
    // Number of results on the Search results page. Zero indicates a 'No Result Search Keyword'. Set to false if you don't know

// We recommend not to call trackPageView() on the Site Search Result page
// _paq.push(['trackPageView']);

We also highly recommend setting the searchCount parameter, as Matomo will specifically report "No Result Keywords", ie. Keywords that were searched, but did not return any result. It is usually very interesting to know what users search for but can't find (yet?) on your website. Learn more about Site Search Analytics in the User Doc.

Custom variables

Custom variables are a powerful feature that enable you to track custom values for each visit, and/or each page view. Please see the Tracking custom variables documentation page for general information.

You can set up up to 5 custom variables (name and value) for each visit to your website, and/or up to 5 custom variables for each page view. If you set a custom variable to a visitor, when they come back one hour or two days later, it will be a new visit and their custom variables will be empty.

There are two "scopes" which you can set your custom variables to. The "scope" is the 4th parameter of the function setCustomVariable().

  • when scope = "visit", the custom variable's name and value will be stored in the visit in the database. You can therefore store up to 5 custom variables of scope "visit" for each visit.
  • when scope = "page", the custom variable's name and value will be stored for the page view being tracked. You can therefore store up to 5 custom variables of scope "page" for each page view.

The "index" parameter is the custom variable slot index, an integer from 1 to 5. (note: read this FAQ if you need more than the default 5 slots).

Custom variable statistics are reported in Matomo under Visitors > custom variables. Both custom variables of scope "visit" and "page" are aggregated in this report.

Custom variables for visits

setCustomVariable(index, name, value, scope = "visit")

This function is used to create, or update a custom variable name and value. For example, imagine you want to store in each visit the gender of the user. You would store the custom variable with a name = "gender", value = "male" or "female".

Important: a given custom variable name must always be stored in the same "index". For example, if you choose to store the variable name = "Gender" in index = 1 and you record another custom variable in index = 1, then the "Gender" variable will be deleted and replaced with the new custom variable stored in index 1.

    // Index, the number from 1 to 5 where this custom variable name is stored
    // Name, the name of the variable, for example: Gender, VisitorType
    // Value, for example: "Male", "Female" or "new", "engaged", "customer"
    // Scope of the custom variable, "visit" means the custom variable applies to the current visit


You only need to set a variable with scope "visit" once, and the value will be recorded for the whole visit.

Custom variable for page views

setCustomVariable(index, name, value, scope = "page")

As well as tracking custom variables for "visits", it is sometimes useful to track custom variables for each page view separately. For example, for a "News" website or blog, a given article may be categorized into one or several categories. In this case, you could set one or several custom variables with name="category", one with value="Sports" and another with value="Europe" if the article is classified in Sports and Europe Categories. The custom variables report will then report on how many visits and page views were in each of your website's categories. This information can be difficult to obtain with standard Matomo reports because they report on "Best Page URLs" and "Best Page Titles" which might not contain the "category" information.

// Track 2 custom variables with the same name, but in different slots.
// You will then access the statistics about your articles' categories in the 'Visitors &gt; custom variables' report
_paq.push(['setCustomVariable', 1, 'Category', 'Sports', 'page']);

// Track the same name but in a different Index
_paq.push(['setCustomVariable', 2, 'Category', 'Europe', 'page']);
// Here you could track other custom variables with scope "page" in Index 3, 4 or 5
// The order is important: first setCustomVariable is called and then trackPageView records the request


Important: It is possible to store a custom variables of scope "visit" in "index" 1, and store a different custom variable of scope "page" in the same "index" 1. Therefore, you can technically track up to 10 custom variables names and values on every page of your website (5 with a "page" scope stored in the actual page view, 5 with a "visit" scope stored in the visit).

    // Index, the number from 1 to 5 where this custom variable name is stored for the current page view
    // Name, the name of the variable, for example: Category, Sub-category, UserType
    // Value, for example: "Sports", "News", "World", "Business", etc.
    // Scope of the custom variable, "page" means the custom variable applies to the current page view


Deleting a custom variable

deleteCustomVariable(index, scope)

If you created a custom variable and then decide to remove this variable from a visit or page view, you can use deleteCustomVariable.

To persist the change in the Matomo server, you must call the function before the call to trackPageView();

_paq.push(['deleteCustomVariable', 1, "visit"]); // Delete the variable in index 1 stored for the current visit

Retrieving a custom variable

getCustomVariable(index, scope)

This function can be used to get the custom variable name and value. By default, it will only work for custom variables that were set during the same page load.

Note: it is possible to configure Matomo so that getCustomVariable will also return the name and value of a custom variable of scope "visit", even when it was set in a previous pageview in the same visit. To enable this behavior, call the JavaScript function storeCustomVariablesInCookie before the call to trackPageView. This will enable the storage of Custom Variables of scope "visit" in a first party cookie. The custom variables cookie will be valid for the duration of the visit (30 minutes after the last action). You can then retrieve the custom variable names and values using getCustomVariable. If there is no custom variable in the requested index, it will return false.

_paq.push([ function() {

    var customVariable = this.getCustomVariable( 1, "visit" );
    // Returns the custom variable: [ "gender", "male" ]

    // do something with customVariable...



Custom Dimensions

Custom Dimensions are a powerful feature that enable you to track custom values for each visit, and/or each action (page view, outlink, download). This feature is not shipped with Matomo directly but can be installed as a plugin via the Matomo Marketplace (CustomDimensions plugin). Before you can use a Custom Dimension you need to install the plugin and configure at least one dimension, see the Custom Dimensions guide. You will get a numeric ID for each configured Custom Dimension which can be used to set a value for it.

Tracking a Custom Dimension across tracking requests

To track a value simply specify the ID followed by a value:

_paq.push(['setCustomDimension', customDimensionId = 1, customDimensionValue = 'Member']);

Please note once a Custom Dimension is set, the value will be used for all following tracking requests and may lead to inaccurate results if this is not wanted. For example if you track a page view, the Custom Dimension value will be as well tracked for each following event, outlink, download, etc. within the same page load. Calling this method will not actually trigger a tracking request, instead the values will be sent along with the following tracking requests. To delete a Custom Dimension value after a tracking request call _paq.push(['deleteCustomDimension', customDimensionId]);

Setting a custom dimension for the initial page view

To set a custom dimension for the initial page view, make sure to position the method call setCustomDimension before trackPageView:

_paq.push(['setCustomDimension', customDimensionId = 1, customDimensionValue = 'Member']);
// _paq.push(['enableLinkTracking']);
// rest of tracking code

Tracking a Custom Dimension for one specific action only

It is possible to set a Custom Dimension for one specific action only. If you want to track a Page view, you can send one or more specific Custom Dimension values along with this tracking request as follows:

_paq.push(['trackPageView', pageTitle, {dimension1: 'DimensionValue'}]);

To define a dimension value pass an object defining one or multiple properties as the last parameter (make sure to specify all parameters as defined in the method, we do not automatically assume the last parameter is customData but instead all parameters that a method defines need to be passed to each method). The property name for a dimension starts with dimension followed by a Custom Dimension ID, for example dimension1. The same behaviour applies for several other methods:

_paq.push(['trackEvent', category, action, name, value, {dimension1: 'DimensionValue'}]);
_paq.push(['trackSiteSearch', keyword, category, resultsCount, {dimension1: 'DimensionValue'}]);
_paq.push(['trackLink', url, linkType, {dimension1: 'DimensionValue'}]);
_paq.push(['trackGoal', idGoal, customRevenue, {dimension1: 'DimensionValue'}]);

The advantage is that the set dimension value will be only used for this particular action and you do not have to delete the value after a tracking request. You may set multiple dimension values like this:

_paq.push(['trackPageView', pageTitle, {dimension1: 'DimensionValue', dimension4: 'Test', dimension7: 'Value'}]);

Retrieving a Custom Dimension value


This function can be used to get the value of a Custom Dimension. It will only work if a Custom Dimension was set during the same page load.

User ID

User ID is a feature in Matomo that lets you connect together a given user's data collected from multiple devices and multiple browsers. There are two steps to implementing User ID:

  • You must assign a unique and persistent non-empty string that represents each logged-in user. Typically, this ID will be an email address or a username provided by your authentication system.
  • You must set the user ID for each pageview, otherwise the pageview will be tracked without the user ID set.
  • You must then pass this User ID string to Matomo via the setUserId method call just before calling any of the track* functions (trackPageview, trackEvent, trackGoal, trackSiteSearch, etc.) for example:
_paq.push(['setUserId', 'USER_ID_HERE']);

Note: USER_ID_HERE must be a unique and persistent non-empty string that represents a user across devices.

When user is logged in, set the User ID

Let's take an example. Imagine that your website authenticate your users via a login form using a PHP script. Here is what your Matomo JavaScript snippet may look like:

var _paq = window._paq = window._paq || [];

// If user is logged-in then call 'setUserId'
// $userId variable must be set by the server when the user has successfully authenticated to your app.
if (isset($userId)) {
     echo sprintf("_paq.push(['setUserId', '%s']);", $userId);


When user logs out, reset User ID

When the user has logged out and a User ID is not available anymore, it is recommended to notify Matomo by calling the resetUserId method before trackPageView.

If you want to create a new visit when your users logout, then you can also force Matomo to create a new Visit by calling resetUserId and appendToTrackingUrl (twice) as below:

// User has just logged out, we reset the User ID _paq.push(['resetUserId']); // we also force a new visit to be created for the pageviews after logout _paq.push(['appendToTrackingUrl', 'new_visit=1']); _paq.push(['trackPageView']); // we finally make sure to not again create a new visit afterwards (important for Single Page Applications) _paq.push(['appendToTrackingUrl', '']);

Content Tracking

There are several ways to track content impressions and interactions manually, semi-automatically and automatically. Please be aware that content impressions will be tracked using bulk tracking which will always send a POST request, even if GET is configured which is the default. For more details have a look at the in-depth guide to Content Tracking.

Track all content impressions within a page

You can use the method trackAllContentImpressions() to scan the entire DOM for content blocks. For each content block we will track a content impression immediately. If you only want to track visible content impression have a look at trackVisibleContentImpressions().


We won't send an impression of the same content block twice if you call this method multiple times unless trackPageView() is called meanwhile. This is useful for single page applications.

Track only visible content impressions within a page.

Enable to track only visible content impressions via trackVisibleContentImpressions(checkOnScroll, timeIntervalInMs). With visible we mean the content block has been in the view port and is not hidden (opacity, visibility, display, ...).

  • Optionally you can tell us to not rescan the DOM after each scroll by passing checkOnScroll=false. Otherwise, we will check whether the previously hidden content blocks became visible meanwhile after a scroll and if so track the impression.
    • Limitation: If a content block is placed within a scrollable element (overflow: scroll), we do currently not detect when such an element becomes visible.
  • Optionally you can tell us to rescan the entire DOM for new content impressions every X milliseconds by passing timeIntervalInMs=500. By default, we will rescan the DOM every 750ms. To disable it pass timeIntervalInMs=0.
    • Rescanning the entire DOM and detecting the visible state of content blocks can take a while depending on the browser, hardware and amount of content. In case your frames per second goes down you might want to increase the interval or disable it completely. In case you disable it you can still rescan the DOM manually at any time by calling this method again or trackContentImpressionsWithinNode().

Both checkOnScroll and timeIntervalInMs cannot be changed after this method was called the first time.

_paq.push(['trackVisibleContentImpressions', true, 750]);

Track content impressions only for a part of the page

Use the method trackContentImpressionsWithinNode(domNode, contentTarget) if you are adding elements to your DOM after we have tracked the initial impressions. Calling this method will make sure an impression will be tracked for all content blocks contained within this node.


var div = $('<div>...<div data-track-content>...</div>...<div data-track-content>...</div></div>');

_paq.push(['trackContentImpressionsWithinNode', div[0]]);

We would detect two new content impressions in this example. In case you have enabled to track only visible content blocks we will respect this.

Track an interaction semi-automatic

Interactions with content blocks are usually tracked automatically as soon as a visitor is clicking on it. Sometimes you might want to trigger an interaction manually for instance in case you want to trigger an interaction based on a form submit or a double click. To do so call the method trackContentInteractionNode(domNode, contentInteraction).


formElement.addEventListener('submit', function () {
    _paq.push(['trackContentInteractionNode', this, 'submittedForm']);
  • The passed domNode can be any node within a content block or the content block element itself. Nothing will be tracked in case there is no content block found.
  • Optionally you can set the name of the content interaction, for instance click or submit. If none is provided, the value Unknown will be used.
  • You should disable the automatic interaction tracking of that content block by setting the CSS class piwikContentIgnoreInteraction or the attribute data-content-ignoreinteraction. Otherwise an interaction might be tracked on top of it as soon as a visitor performs a click.

We call this kind of tracking semi-automatic as you triggered the interaction manually but the content name, piece and target is detected automatically. Detecting the content name and piece automatically makes sure we can map the interaction with a previously tracked impression.

Tracking content impressions and interactions manually

You should use the methods trackContentImpression(contentName, contentPiece, contentTarget) and trackContentInteraction( contentInteraction, contentName, contentPiece, contentTarget) only in conjunction together. It is not recommended to use trackContentInteraction() after an impression was tracked automatically as we can map an interaction to an impression only if you do set the same content name and piece that was used to track the related impression.


_paq.push(['trackContentImpression', 'Content Name', 'Content Piece', '']);

div.addEventListener('click', function () {
    _paq.push(['trackContentInteraction', 'tabActivated', 'Content Name', 'Content Piece', '']);

Be aware that each call to those methods will send one request to your Matomo tracker instance. Doing this too many times can cause performance problems.

Measuring domains and/or sub-domains

Whether you are tracking one domain, or a subdomain, or both at the same time, etc. you may need to configure the Matomo JavaScript tracking code. There are two things that may need to be configured: 1) how tracking cookies are created and shared, and 2) which clicks should be tracked as 'Outlinks'.

Tracking one domain

This is the standard use case. Matomo tracks the visits of one domain name with no subdomain, in a single Matomo website.

// Default Tracking code
_paq.push(['setSiteId', 1]);
_paq.push(['setTrackerUrl', u+'matomo.php']);

If you are tracking one specific subdomain, this default tracking code also works.

Tracking one domain and its subdomains in the same website

To record users across the main domain name and any of its subdomains, we tell Matomo to share the cookies across all subdomains. setCookieDomain() is called in the Matomo tracking code in* and all subdomains.

_paq.push(['setSiteId', 1]);
_paq.push(['setTrackerUrl', u+'matomo.php']);

// Share the tracking cookie across,,, ...
_paq.push(['setCookieDomain', '*']);

// Tell Matomo the website domain so that clicks on these domains are not tracked as 'Outlinks'
_paq.push(['setDomains', '*']);


Tracking your visitors across multiple domain names in the same website

To accurately track a visitor across different domain names into a single visit within one Matomo website, we need to set up what is called Cross Domain linking. Cross domain tracking in Matomo makes sure that when the visitor visits multiple websites and domain names, the visitor data will be stored in the same visit and that the visitor ID is reused across domain names. A typical use case where cross domain is needed is, for example, when an ecommerce online store is on and the ecommerce shopping cart technology is on another domain such as

Cross domain linking uses a combination of the two tracker methods setDomains and enableCrossDomainLinking. Learn how to set up cross-domain linking in our guide: How do I accurately measure a same visitor across multiple domain names (cross domain linking)?

Tracking subdirectories of a domain in separate websites

When tracking subdirectories of a domain in their own separate Matomo website, it is recommended to customise the tracking code to ensure optimal data accuracy and performance.

For example, if your website offers a 'User profile' functionality, you may wish to track each user profile pages in a separate website in Matomo. In the main domain homepage, you would use the default tracking code:

// idSite = X for the Homepage
// In Administration > Websites for idSite=X, the URL is set to ``
_paq.push(['setSiteId', X]);
_paq.push(['setTrackerUrl', u+'matomo.php']);

In the page (and in every other user profile), you would construct calls to custom setSiteId, setCookiePath and setDomains:

// The idSite Y will be different from other user pages
// In Administration > Websites for idSite=Y, the URL is set to ``
_paq.push(['setSiteId', Y]);

// Create the tracking cookie specifically in ``
_paq.push(['setCookiePath', '/user/MyUsername']);

// Tell Matomo the website domain so that clicks on other pages (eg. /user/AnotherUsername) will be tracked as 'Outlinks'
_paq.push(['setDomains', '']);

_paq.push(['setTrackerUrl', u+'matomo.php']);

When tracking many subdirectories in separate websites, the function setCookiePath prevents the number of cookies to quickly increase and prevent browser from deleting some of the cookies. This ensures optimal data accuracy and improves performance for your users (fewer cookies are sent with each request).

The functionsetDomains ensures that clicks of users leaving your website (subdirectory are correctly tracked as 'Outlinks'.

Tracking a group of pages in a separate website

(available since Matomo 2.16.1)

In some rare cases, you may want to track all pages matching a wildcard in a particular website, and track clicks on other pages (not matching the wildcard) as 'Outlinks'.

In the pages /index_fr.htm or /index_en.htm write:

// clicks on links not starting with will be tracked as 'Outlinks'
_paq.push(['setDomains', '*']);

// when using a wildcard *, we do not need to configure cookies with `setCookieDomain`
// or `setCookiePath` as cookies are correctly created in the main domain by default

_paq.push(['setTrackerUrl', u+'matomo.php']);


  • the wildcard * is supported only when specified at the end of the string.
  • since the wildcard can match several paths, calls to setCookieDomain or setCookiePath are omitted to ensure tracking cookie is correctly shared for all pages matching the wildcard.

For more information about tracking websites and subdomains in Matomo, see the FAQ: How to configure Matomo to monitor several websites, domains and sub-domains

The default Matomo JavaScript tracker code automatically enables the download & outlink tracking automatically, which is done by calling the enableLinkTracking function:

// Enable Download & Outlink tracking _paq.push(['enableLinkTracking']);

It is recommended to add this line just after the first call to trackPageView or trackEvent.

By default all links to domains other than the current domain have click tracking enabled, and each click will be counted as an outlink. If you use multiple domains and subdomains, you may see clicks on your subdomains appearing in the Pages > Outlinks report.

If you only want clicks to external websites to appear in your outlinks report, you can use the function setDomains() to specify the list of alias domains or subdomains. Wildcard domains (* are supported to let you easily ignore clicks to all subdomains.

// Don't track Outlinks on all clicks pointing to * or *
// Note: the currently tracked website is added to this array automatically
_paq(['setDomains', ["*", ""]]);


Since Matomo 2.15.1 you may also append a path to a domain and Matomo will correctly detect links to the same domain but different path as an outlink.

// Don't track Outlinks on all clicks pointing to ** or **
// Track all clicks not pointing to ** or ** as outlink.
_paq(['setDomains', ["*", ""]]);

Learn more about this use case Tracking subdirectories of a domain in separate websites.

If you want to force Matomo to consider a link as an outlink (links to the current domain or to one of the alias domains), you can add the matomo_link or piwik_link css class to the link:

<a href='' class='matomo_link'>Link I want to track as an outlink</a>

Note: you can customize and rename the CSS class used to force a click to be recorded as an outlink:

// now all clicks on links with the css class "external" will be counted as outlinks

// you can also pass an array of strings
_paq.push(['setLinkClasses', "external"]);


Alternatively, you can use JavaScript to manually trigger a click on an outlink (it will work the same for page views or file downloads). In this example, custom outlink is trigged when the email address is clicked:

<a href="" target="_blank" onClick="_paq.push(['trackLink', ' namexyz', 'link']);"> </a>

Tracking file downloads

By default, any file ending with one of these extensions will be considered a 'download' in the Matomo interface:


Customise the type of files tracked as downloaded

To replace the list of extensions you want to track as file downloads, you can use setDownloadExtensions( string ):

// we now only track clicks on images
_paq.push(['setDownloadExtensions', "jpg|png|gif"]);


If you want to track a new file type, you can just add it to the list by using addDownloadExtensions( filetype ):

// clicks on URLs finishing by mp5 or mp6 will be counted as downloads
_paq.push(['addDownloadExtensions', "mp5|mp6"]);

If you want to ignore a special file type, you can just remove it from the list by using removeDownloadExtensions( filetype ):

// clicks on URLs ending in png or mp4 will not be counted as downloads
_paq.push(['removeDownloadExtensions', "png|mp4"]);

Recording a click as a download

If you want to force Matomo to consider a link as a download, you can add the matomo_download or piwik_download css class to the link:

<a href='last.php' class='matomo_download'>Link I want to track as a download</a>

Note: you can customize and rename the CSS class used to force a click to be recorded as a download:

// now all clicks on links with the css class "download" will be counted as downloads

// you can also pass an array of strings
_paq.push(['setDownloadClasses', "download"]);


Alternatively, you can use JavaScript to manually trigger a click on a download. In this example, custom download is trigged when the link is clicked:

<a href="" target="_blank" onClick="_paq.push(['trackLink', ' namexyz', 'download']);">Download</a>

Changing the Pause Timer

When a user clicks to download a file, or clicks on an outbound link, Matomo records it. In order to do so, it adds a small delay before the user is redirected to the requested file or link. The default value is 500ms, but you can set it to a shorter length of time. It should be noted, however, that doing so results in the risk that this period of time is not long enough for the data to be recorded in Matomo.

_paq.push(['setLinkTrackingTimer', 250]); // 250 milliseconds


By default, the Matomo tracking code enables clicks and download tracking. To disable all automatic download and outlink tracking, you must remove the call to the enableLinkTracking() function:


// we comment out the function that enables link tracking
// _paq.push(['enableLinkTracking']);

Disabling for specific CSS classes

You can disable automatic download and outlink tracking for links with specific CSS classes:

 // you can also pass an array of strings
_paq.push(['setIgnoreClasses', "no-tracking"]);

This will result in clicks on a link <a href='' class='no-tracking'>Test</a> not being counted.

If you want to ignore download or outlink tracking on a specific link, you can add the matomo_ignore or 'piwik_ignore' css class to it:

<a href='' class='matomo_ignore'>File I don't want to track as a download</a>

View our integration guide for implementing tracking or cookie consent.

View the opt-out guide for implementing an opt-out form using the built-in Matomo options

Optional: creating a custom opt-out form

If you'd like to provide your users with the ability to opt-out entirely from tracking, you can use an opt-out form. Matomo ships with an opt-out form implementation that uses third-party cookies (which you can configure within Matomo on the Matomo > Administration > Privacy page).

This form is simple to embed since it only requires that you add an iframe to your website, but it is not always ideal. Some users block third-party cookies so the opt-out form wouldn't work for them. You may also want to display custom text or graphics in the opt-out form, or you may want to allow users to opt-out of your sites individually instead of altogether.

In such a case, you may want to consider creating a custom opt-out form. The specifics of creating an HTML/JS form are out of scope for this document, but there are some things every custom opt-out form will have to do: check if the user is currently opted out, opt a user out and opt a user in. Here is how to do those things:

check if the user is currently opted out

Use the isUserOptedOut() method like so:

_paq.push([function () {
  if (this.isUserOptedOut()) {
    // ... change form to say user is currently opted out ...
  } else {
    // ... change form to say user is currently opted in ...

opt a user out

Use the optUserOut() method:


opt a user in

Use the forgetUserOptOut() method:


Below is an example opt-out form that replicates the built in Matomo opt-out form:

<div id="optout-form">
  <p>You may choose not to have a unique web analytics cookie identification number assigned to your computer to avoid the aggregation and analysis of data collected on this website.</p>
  <p>To make that choice, please click below to receive an opt-out cookie.</p>

    <input type="checkbox" id="optout" />
    <label for="optout"><strong></strong></label>
document.addEventListener("DOMContentLoaded", function(event) {
  function setOptOutText(element) {
    _paq.push([function() {
      element.checked = !this.isUserOptedOut();
      document.querySelector('label[for=optout] strong').innerText = this.isUserOptedOut()
        ? 'You are currently opted out. Click here to opt in.'
        : 'You are currently opted in. Click here to opt out.';

  var optOut = document.getElementById("optout");
  optOut.addEventListener("click", function() {
    if (this.checked) {
    } else {

Multiple Matomo trackers

By default, the Matomo JavaScript Tracking code collects your analytics data into one Matomo server. The Matomo service URL is specified in your JavaScript Tracking code (for example: var u="//";). In some cases, you may want to track your analytics data into more than just one Matomo server or into multiple websites on the same Matomo server.

If you haven't upgraded yet to Matomo 2.16.2 or later, please upgrade now! (Instructions for 2.16.1 or older versions are found below.)

Duplicate your data into different websites in one Matomo server

You may need to collect a duplicate of your web analytics data into the same Matomo server, but in another website.

When you need to duplicate data into another website, or consolidate several websites into one or more groups (called RollUps) the recommended solution is to use the RollUp Reporting premium plugin. Using this plugin has several advantages over the other solution as you can easily group one or more websites together, and the RollUps do not cause the tracking data to be duplicated which improves overall performance.

Alternative solution: duplicate the tracking data

Alternatively to using the RollUp Reporting plugin you can duplicate the tracking data. To duplicate the data you can call addTracker with a Matomo URL and your website ID where to duplicate the data:

  var u="//";
  _paq.push(['setTrackerUrl', u+'matomo.php']);
  _paq.push(['setSiteId', '1']);

  // We will also collect the website data into Website ID = 7
  var websiteIdDuplicate = 7;
  // The data will be duplicated into ``
  _paq.push(['addTracker', u+'matomo.php', websiteIdDuplicate]);
  // Your data is now tracked in both website ID 1 and website 7 into your server!

As this solution causes every visitor's event, pageview, etc. to be tracked twice in your Matomo server, we generally do not recommend it.

Collect your analytics data into two or more Matomo servers

The example below shows how to use addTracker method to track the same analytics data into a second Matomo server. The main Matomo server is where the data is stored into website ID 1. The second Matomo server is where the data is stored into website ID 77. When you implement this in your website, please replace these two Matomo URLs and Matomo website IDs with your own Matomo URLs and website IDs.

<script type="text/javascript">
  var _paq = window._paq = window._paq || [];

  (function() {
    var u="//";
    _paq.push(['setTrackerUrl', u+'matomo.php']);
    _paq.push(['setSiteId', '1']);

    // Add this code below within the Matomo JavaScript tracker code
    // Important: the tracker url includes the /matomo.php
    var secondaryTrackerUrl = '';
    var secondaryWebsiteId = 77;
    // Also send all of the tracking data to this other Matomo server, in website ID 77
    _paq.push(['addTracker', secondaryTrackerUrl, secondaryWebsiteId]);
    // That's it!

    var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
    g.type='text/javascript'; g.async=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s);

Customise one of the tracker object instances

Note: by default any tracker added via addTracker is configured the same as the main default tracker object (regarding cookies, custom dimensions, user id, download & link tracking, domains and sub-domains, etc.). If you want to configure one of the Matomo tracker object instances that was added via addTracker, you may call the Matomo.getAsyncTracker(optionalMatomoUrl, optionalPiwikSiteId) method. This method returns the tracker instance object which you can configure differently than the main JavaScript tracker object instance.

Duplicate the tracking data when calling the JavaScript API directly (not via _paq.push)

It is possible to track your analytics data into either a different website ID on the same server or you may record a copy of your data into another Matomo server altogether. Each call to Matomo.getTracker() returns a unique Matomo Tracker object (instance) which can be configured.

<script type="text/javascript">
    window.matomoAsyncInit = function () {
        try {
            var matomoTracker = Matomo.getTracker("https://URL_1/matomo.php", 1);
            var piwik2 = Matomo.getTracker("https://URL_2/matomo.php", 4);
        } catch( err ) {}

The matomoAsyncInit() method will be executed once the Matomo tracker is loaded and initialized. In earlier versions you must load Matomo synchronous.

JavaScript Tracker Reference

View all features of the Tracking client in the JavaScript Tracker Reference.

Frequently Asked Questions

If you have any question about JavaScript Tracking in Matomo, please search the website, or ask in the forums.