What is the _sp_ses cookie?
_sp_ses is a cookie used by Snowplow, a data analytics (event tracking) platform used by websites and apps to collect user behavior events such as page views, clicks, and form interactions.
The full cookie name includes an identifier tied to the specific Snowplow setup (such as a collector or site ID), so it may appear slightly differently on each site, but it always starts with the _sp_ses prefix. It is set automatically by the Snowplow JavaScript tracker when the page first loads or the first event fires, provided the visitor has consented to statistics cookies.
What data it stores
_sp_ses typically stores a simple marker value (for example, „1” or a boolean-style flag) indicating that a tracking session is currently active, rather than the actual event content. The exact value format can vary depending on each site's Snowplow configuration and isn't publicly documented in detail.
The actual event data collected by Snowplow (pages visited, user actions, session and device identifiers) is sent to the Snowplow collector endpoint configured by the site owner, which may be hosted by the provider, a third party, or on the company's own self-hosted infrastructure.
What it is used for
Its main purpose is session delimitation: Snowplow uses _sp_ses together with a longer-lived identity cookie to group events into a coherent session and determine whether a visit is new or a continuation of a recent one.
For the site owner, this data feeds traffic reports, user behavior analysis, A/B testing, or content personalization, depending on how the Snowplow deployment is configured.
Does it require consent?
_sp_ses is classified as a statistics (analytics) cookie. Since it is not strictly necessary for the site's technical operation, under the ePrivacy Directive (transposed in Romania via Law 506/2004) and GDPR it requires the visitor's prior, explicit consent before being set.
- The site owner must declare it accurately in the cookie policy, under the statistics category.
- The Snowplow script must only load after the visitor gives consent, not on initial page load.
- Rejecting consent must be as easy as accepting it, and withdrawal must be possible at any time.
How to block or delete _sp_ses
A visitor can manually delete or block _sp_ses through their browser's cookie settings (Chrome, Firefox, Safari, Edge), either by clearing cookies for that site or by enabling third-party cookie and tracking-script blocking.
For site owners, the correct approach isn't manual deletion but preventing the cookie from being set before consent. A CMP like CookieFix automatically blocks the Snowplow script (and by extension the _sp_ses cookie) until the visitor explicitly accepts the „statistics” category in the banner, ensuring the legally required order: consent before tracking.
Frequently asked questions
It's a session cookie set by the Snowplow analytics platform that flags whether a user's visit is currently active, used to group tracking events into sessions.
It typically lasts 30 minutes from the last activity; if the visitor stays inactive longer, the session expires and a new one starts with the next action.
Its stored value alone isn't sensitive, but it's part of a behavioral tracking system that, combined with other Snowplow cookies, can indirectly identify a visitor, which is why it's treated as personal data under GDPR.
Yes. As a statistics cookie, it isn't strictly necessary and requires the visitor's prior consent under ePrivacy and GDPR, with automatic blocking until acceptance.