How do AB Tasty cookies work?

AB tasty uses first-party cookies that are defined by the URL of the website using AB Tasty. 
Cookies enable AB Tasty to work properly and guarantee campaign reliability by recognizing a visitor as unique each time they visit the website (AB Tasty remembers that it is the same visitor without actually knowing who it is).
Cookies log the campaign variation the visitor has been assigned to, to be able to direct them back to the same variation during their future visits. This system avoids behavioral differences and thus misleading results. These cookies don’t store any information on the visitor’s identity.
AB Tasty relies on two different cookies to collect and store data about visitors: ABTasty and ABTastySession. AB Tasty also uses technical cookies to operate properly, read more about this in the corresponding section below.

ABTasty cookie

This is a first-party cookie that has a lifetime of 13 months. The ABTasty cookie has two parts:  

• the first includes data and details about the visitor:

• the second includes information about the campaign the visitor has been allocated to:

ABTastySession cookie

This is a first-party cookie whose the lifetime depends on the duration of the session (a session ends after 30 minutes of inactivity on the website). Its purpose is to collect information about each user’s session. 
A fourth parameter may be present: the referrer. This stores the URL the visitor came from before landing on the website. This data is only available when the “source” or “source type” criteria are being used in the targeting of an active campaign.

Storage method

AB Tasty enables you to modify a cookies’ validity period. To do so, go to Settings > Advanced settings > Cookies > Select Storage Method.

Switching from Cookie to localStorage should not lead to any issues. We are doing an automatic data migration from the cookie to the localStorage and vice-versa. However, the localStorage method is not compatible with cross-domain tracking. In this case, data can’t be shared between subdomains. 

ABTastyOptout cookie

When a visitor doesn’t want to be assigned to any campaigns, they can opt-out by adding the “#abtastyoptout=1” parameter at the end of the website URL.
For example: http://www.abtasty.com/#abtastyoptout=1

Using this parameter creates a cookie in their browser that stores the opt-out information. For more information about this, please refer to How can I avoid being assigned to the tests (optout)?

Technical cookies

The tag is setting several cookies in order to validate that it will be able to operate on the website. Some cookies tracking third-party tools might also discover the regular ABTasty and ABTastySession cookies even without consent being granted, this is because of the way it is technically working and is explained in the section below.

These technical cookies are not used to store data about the visitor and don't even contain anything for most of them. Moreover, their lifetime never exceeds a few milliseconds.

Checking the ability to set cookies

AB Tasty can't work with cookies. To avoid crashing and sending unexpected error messages, the tag first checks if it can write cookies in the current session.

The ABTasty cookie is created with a dummy value and then immediately removed if it succeeded. 

If the operation is failing, the tag will stop its execution and logs the information if you are using the debug module.

Checking the domain validity

The tag then validates which domain it is executing on and if it matches its settings. This is done to avoid any tracking issue or unexpected further failure.

It creates the ABTastyDomainTest cookie with no value. If the operation is a success, it is immediately removed.

If the operation failed, the tag won't go further and will log the information if you are using the debug module.

Consent management specificities

If consent is lost during the visitor's journey, AB Tasty has to erase all data stored for this visitor. To avoid losing any time and not risk any failure in this process, the tag doesn't bother checking if there is already existing data.

All cookies are erased, whether or not they exist. This means that the tag is setting both ABTasty and ABTastySession cookies with an already expired date. For the browser, this consists of creating a cookie that is immediately removed due to its expiration date.

This results in both cookies being declared even without consent and for a very short period of time (in microseconds).

Some cookies tracking third-party tools might detect these "ghost" cookies without consent. We advise setting a lifetime threshold to filter them out.

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For all the technical information and knowledge about AB Tasty cookies and storage, read the complete article on our developer portal.