> For the complete documentation index, see [llms.txt](https://docs.mediarithmics.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mediarithmics.io/setup-and-monitor/ensure-privacy-and-compliance/audit-our-tag-s-browser-footprint.md).

# Audit our tag's browser footprint

The cookies, local storage variables, and calls the tag uses - for your cookie policy and your audits.

## Your goal

Document exactly what the mediarithmics tag places in a browser and which calls it makes, so your cookie policy, your CMP configuration, and your audit answers are accurate.

## Expected outcome

A footprint you can hand to your legal team or an auditor, matching what a browser inspection actually shows.

## What the tag relies on

Tracking capabilities rely on **first-party cookies, third-party cookies, and local storage variables** to identify browsers and capture their activity.

{% hint style="danger" %}
The cookies used by the tag are considered **advertising cookies**. **You must obtain user consent before using it.** See [Manage consent & Processing activities](/setup-and-monitor/ensure-privacy-and-compliance/manage-consent-and-processing-activities.md).
{% endhint %}

## Cookies on the third-party domain

Created on `.mediarithmics.com`, or on your custom domain if you use one.

| Cookie      | What it is                                                                                                                                                                         | Life duration |
| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- |
| `mics_vid`  | The mediarithmics third-party cookie identifier.                                                                                                                                   | 1 year        |
| `mics_lts`  | The last time the browser was seen.                                                                                                                                                | 1 year        |
| `mics_uaid` | Legacy cookie, to be deprecated.                                                                                                                                                   | 1 year        |
| `chk`       | Written when a call reaches `events.mediarithmics.com` without a `mics_vid` cookie, to check whether the browser supports third-party cookies. Contains a randomly generated UUID. | 1 hour        |

## Cookies on the first-party domain

Created on websites where the JavaScript tag is installed.

| Cookie                                             | What it is                                                                                                   | Life duration |
| -------------------------------------------------- | ------------------------------------------------------------------------------------------------------------ | ------------- |
| `mics_vid`                                         | A duplicate of the third-party identifier of the same name, used for **caching** to avoid unnecessary calls. | 6 months      |
| `mics_lts`                                         | The last time the browser was seen.                                                                          | 6 months      |
| `mics_<custom_cookie_name>` or `mics_<site_token>` | The first-party identifier for the browser - the **installation ID**.                                        | 6 months      |

{% hint style="info" %}
`mics_vid` on the first-party domain and the installation ID are **two different mechanisms**. The first is a cache of the third-party cookie and happens systematically; the second is a distinct first-party identifier, only created when you activate it per channel. See [Web tracking](/setup-and-monitor/collect-and-manage-your-data/collect-data-in-real-time/web-tracking.md#device-identification).
{% endhint %}

## Local storage variables

Used only on websites where the JavaScript tag is installed.

| Key                    | What it stores                                                                                                                                                                                   |
| ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `_mediarithmics`       | Per site token: `lastFeedRefreshDate`. Created only if you have added `syncFeeds`.                                                                                                               |
| `<site_token>_mics_up` | **Only present if Edge is activated.** User data structured as a UserPoint model: device characteristics, the browsing history on the first-party website, and the segments the user belongs to. |
| `mics_sgmts`           | **Only present if Edge is activated.** The list of segments the user belongs to - a duplicate of part of the variable above.                                                                     |

{% hint style="warning" %}
The Edge variables are the largest part of the footprint, and the one most likely to surprise an auditor: the browsing history is held **client-side**, with no automatic expiration. Their storage limits are documented in [Edge](/setup-and-monitor/plan-and-integrate/set-up-advanced-features/edge.md#what-is-stored-in-the-browser).
{% endhint %}

## Client-side feeds

Client-side feeds are connectors that load additional JavaScript - provided by mediarithmics or by a partner - in the user's browser.

{% hint style="info" %}
If you use client-side feeds, **additional cookies and local storage variables are likely to be created** by those third parties. They are not in the tables above, and you have to account for them separately. Their documentation is in the `Audience & Activation` section, under feeds.
{% endhint %}

## The calls the tag makes

{% tabs %}
{% tab title="Standard tracking" %}

| URL                                                             | What it does                                                                                                                                                              |
| --------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `static.mediarithmics.com/tag/1/tag.min.js`                     | The static JavaScript tag, containing the implementation of the methods used in the snippet.                                                                              |
| `events.mediarithmics.com/v1/conf.js`                           | Configuration parameters for the tag on the website. Also contains a randomly generated first-party identifier - the installation ID.                                     |
| `events.mediarithmics.com/v1/sites/<site_token>/external_feeds` | Checks whether the user belongs to a segment with a tag feed attached.                                                                                                    |
| `cookie-matching.mediarithmics.com/v1/gather_id`                | Starts the cookie-matching process with Google and Xandr, if activated.                                                                                                   |
| `cookie-matching.mediarithmics.com/input`                       | Ends the cookie-matching process by inputting the ID.                                                                                                                     |
| `cookie-matching.mediarithmics.com/v1/getids`                   | Asks for the creation of the third-party cookie identifier `mics_vid`. If cookie matchings with partners are configured, the response installs pixels for those partners. |
| `events.mediarithmics.com/v1/visits/pixel`                      | Creates a tracking event in the datamart related to the site.                                                                                                             |
| {% endtab %}                                                    |                                                                                                                                                                           |

{% tab title="With Edge activated" %}

| URL                                                         | What it does                                                   |
| ----------------------------------------------------------- | -------------------------------------------------------------- |
| `events.mediarithmics.com/v1/device_info.js`                | Translates the browser user agent into device characteristics. |
| `static.mediarithmics.com/tag/2/evaluator.min.js`           | Downloads the local segment evaluator.                         |
| `events.mediarithmics.com/v1/sites/<site_token>/segment.js` | Downloads the definition of Edge segments.                     |
| {% endtab %}                                                |                                                                |

{% tab title="Possible redirects" %}
These may occur during the process:

* `events.mediarithmics.com/v1/check_cookie/pixel`
* `events.mediarithmics.com/v1/update_mapping/pixel`
* `cookie-matching.mediarithmics.com/v1/get_or_create`
  {% endtab %}
  {% endtabs %}

## How to run the audit

{% stepper %}
{% step %}

### List what your configuration actually enables

The footprint is not fixed: cookie matching, the first-party cookie, Edge, and client-side feeds each add to it, and each is a setting you control. Start from your channel configuration.
{% endstep %}

{% step %}

### Inspect a browser session

Compare the cookies and local storage keys you observe against the tables above. Anything you see that is not listed comes from a client-side feed or another tool.
{% endstep %}

{% step %}

### Check the order against consent

Confirm that nothing is set before consent is given, and that your CMP blocks the tag rather than only signalling to it - unless you rely on the tag's TCF support, in which case check it is enabled on the channel.
{% endstep %}

{% step %}

### Write it into your cookie policy

Names, purposes, and durations, per domain.
{% endstep %}
{% endstepper %}

## Related pages

<table data-view="cards" data-search="false"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Web tracking</strong></td><td>The settings that change this footprint.</td><td><a href="/setup-and-monitor/collect-and-manage-your-data/collect-data-in-real-time/web-tracking.md">Web tracking</a></td></tr><tr><td><strong>Edge</strong></td><td>What is held client-side, and for how long.</td><td><a href="/setup-and-monitor/plan-and-integrate/set-up-advanced-features/edge.md">Edge</a></td></tr><tr><td><strong>User Device</strong></td><td>The identifier formats behind these cookies.</td><td><a href="/setup-and-monitor/collect-and-manage-your-data/design-your-data-model-and-schema/user-identity/user-identifiers/user-device.md">User Device</a></td></tr></tbody></table>


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