Data Storage in Cookies

Detailed technical documentation on persistent user data stored in cookies or local storage by the RudderStack’s JavaScript SDK.

By default, the RudderStack JavaScript SDK stores persistent user data in the cookies. If the cookies are not supported, local storage is used instead.

All the cookies are stored in the top-level domain by default. It helps you to identify the users visiting from websites hosted under a particular sub-domain. For example, if you include the JavaScript SDK in both admin.samplewebsite.com and app.samplewebsite.com, the SDK will store the cookie in samplewebsite.com. However, you can configure where you want to store the cookie by using the setCookieDomain parameter in the load API options as shown:

rudderanalytics.load(<WRITE_KEY>, <DATA_PLANE_URL>, {
  setCookieDomain: "samplewebsite.com",
});

Cookies

The list of cookies used by the JavaScript SDK to store persistent user data is mentioned below:

Name Description Example Clearing mechanism using the SDK

Name	Description	Example	Clearing mechanism using the SDK
`rl_user_id`	Stores the user ID set via the `identify` API. All the subsequent event payloads will contain this data unless cleared from the storage.	`4578`, `USER_001`	`rudderanalytics.reset()`
`rl_trait`	Stores the user traits object set via the `identify` API. All the subsequent event payloads will contain this data unless cleared from the storage.	`{ email: "alex@example.com", accountType: "pro", country: "US", someObj: { key1: val1, key2: val2, }}`	`rudderanalytics.reset()`
`rl_anonymous_id`	Stores the anonymous ID. By default, it would be the auto-generated unique ID by SDK for each visitor unless overridden via `setAnonymousId` API. All the subsequent event payloads will contain this data unless cleared from the storage.	`5bfe258f-bd2f-49cf-bddd-8b844f74ab4b`, `customAnonId`	`rudderanalytics.reset(true)`
`rl_group_id`	Stores the user group ID set via the `group` API. All the subsequent group event payloads will contain this data unless cleared from the storage.	`GRP_3`, `98`	`rudderanalytics.reset()`
`rl_group_trait`	Stores the user group traits object set via the `group` API. All the subsequent group event payloads will contain this data unless cleared from the storage.	`{ location: "New Orleans", nationality: "US", someObj: { key1: val1, key2: val2, }}`	`rudderanalytics.reset()`
`rl_page_init_referrer`	Stores the initial referrer of the page when a user visits a site for the first time. All the subsequent event payloads will contain this data.	`https://www.google.com/`	Cannot be cleared using SDK.
`rl_page_init_referring_domain`	Stores the initial referring domain of the page when a user visits a site for the first time. All the subsequent event payloads will contain this data.	`google.com`	Cannot be cleared using SDK.
`test_rudder_cookie`	Checks whether the cookie storage of a browser is accessible or not. Once checked, this cookie is removed immediately.	`test_rudder_cookie:true`	Cleared automatically.

rl_user_id

Stores the user ID set via the identify API. All the subsequent event payloads will contain this data unless cleared from the storage.

4578, USER_001

rudderanalytics.reset()

rl_trait

Stores the user traits object set via the identify API. All the subsequent event payloads will contain this data unless cleared from the storage.

{  email: "alex@example.com",  accountType: "pro",  country: "US",  someObj: {    key1: val1,    key2: val2,  }}

rudderanalytics.reset()

rl_anonymous_id

Stores the anonymous ID. By default, it would be the auto-generated unique ID by SDK for each visitor unless overridden via setAnonymousId API. All the subsequent event payloads will contain this data unless cleared from the storage.

5bfe258f-bd2f-49cf-bddd-8b844f74ab4b, customAnonId

rudderanalytics.reset(true)

rl_group_id

Stores the user group ID set via the group API. All the subsequent group event payloads will contain this data unless cleared from the storage.

GRP_3, 98

rudderanalytics.reset()

rl_group_trait

Stores the user group traits object set via the group API. All the subsequent group event payloads will contain this data unless cleared from the storage.

{  location: "New Orleans",  nationality: "US",  someObj: {    key1: val1,    key2: val2,  }}

rudderanalytics.reset()

rl_page_init_referrer

Stores the initial referrer of the page when a user visits a site for the first time. All the subsequent event payloads will contain this data.

https://www.google.com/

Cannot be cleared using SDK.

rl_page_init_referring_domain

Stores the initial referring domain of the page when a user visits a site for the first time. All the subsequent event payloads will contain this data.

google.com

Cannot be cleared using SDK.

test_rudder_cookie

Checks whether the cookie storage of a browser is accessible or not. Once checked, this cookie is removed immediately.

test_rudder_cookie:true

Cleared automatically.

The cookie values are encrypted and their length is directly proportional to the values provided to the SDK. Also, all the cookie names are prefixed with rl_ and the values are prefixed with RudderEncrypt:. For example, rl_user_id —> RudderEncrypt:U2FsdGVkX1+UKmiooYoGmKdNws7sgmWgGfHe.

Local storage cookies

The local storage cookies are used by the JavaScript SDK to keep track of the events sent to the RudderStack backend. They are listed in the table below:

Name Description Example

Name	Description	Example
`ack`	Timer for other browser tabs to claim control of the retry queue.	`1639734070124`
`reclaimStart` and `reclaimEnd`	Determines if a tab takes over the queue from another tab.	`2dc2aee6-2836-4273-be69-79c90c04ddec`
`inProgress`	Keeps track of the events in progress.	`{ "d89d7fb5-945e-4378-bda5-492e4b596fb4": { "item": { "url": "https://rudderstack-dataplane.rudderstack.com/v1/track", "headers": { "Content-Type": "application/json", ... }, "message": { ... } "attemptNumber": 1, "time": 1639734792773, "id": "a4d89d7f-b594-4eb3-b8bd-a5492e4b596f" } }}`
`queue`	Keeps track of the events that are in queue to be processed.	`[ { "item": { "url": "https://rudderstack-dataplane.rudderstack.com/v1/track", "headers": { "Content-Type": "application/json", ... }, "message": { ... } "attemptNumber": 0, "time": 1639734792773, "id": "a4d89d7f-b594-4eb3-b8bd-a5492e4b596f" } }]`

ack

Timer for other browser tabs to claim control of the retry queue.

1639734070124

reclaimStart and reclaimEnd

Determines if a tab takes over the queue from another tab.

2dc2aee6-2836-4273-be69-79c90c04ddec

inProgress

Keeps track of the events in progress.

{  "d89d7fb5-945e-4378-bda5-492e4b596fb4": {   "item": {    "url": "https://rudderstack-dataplane.rudderstack.com/v1/track",    "headers": {     "Content-Type": "application/json",      ...    },    "message": {      ...    }    "attemptNumber": 1,    "time": 1639734792773,    "id": "a4d89d7f-b594-4eb3-b8bd-a5492e4b596f"   }  }}

queue

Keeps track of the events that are in queue to be processed.

[  {   "item": {    "url": "https://rudderstack-dataplane.rudderstack.com/v1/track",    "headers": {     "Content-Type": "application/json",      ...    },    "message": {      ...    }    "attemptNumber": 0,    "time": 1639734792773,    "id": "a4d89d7f-b594-4eb3-b8bd-a5492e4b596f"   }  }]

All the local storage cookie names are prefixed with rudder.<uuid>. For example, rudder.2dc2aee6-2836-4273-be69-79c90c04ddec.reclaimEnd.

FAQ

Refer to the FAQ section for solutions to some of the commonly faced issues while using the JavaScript SDK on your website.

Contact us

For more information or queries on this guide, you can contact us or start a conversation in our Slack community.

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Last updated 2 years ago