<aside> <img src="/icons/info-alternate_green.svg" alt="/icons/info-alternate_green.svg" width="40px" /> This page explains Prolific’s Cookie Notice. Our website uses cookies and other storage and access technologies to help us provide you with a good experience when you browse our website (which includes using the Prolific platform as a Researcher or Participant) and also allows us to make improvements to our website. To the extent that our use of such technologies constitute the processing of personal data, please refer to our Privacy Notices for more information.
Last updated 29 July 2026.
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When you use Prolific, it will store data on your device by two methods: web storage and cookies.
Web storage is a type of storage and access technology. It is a way in which online services can store information, or access information stored, on your device. It involves websites storing data within your browser.
A cookie is a small text file, which is stored on the device you use to access a website. The device can store cookies (via the web browser) and send information back when you next make a request to the same web server. You can read more about web storage here and about cookies here.
The web storage and cookies we use allow us to monitor and analyse your use of the website and to help improve our product features and service offering. The following section describes what kinds of web storage and cookies we use.
We use web storage technologies to enhance your experience on Prolific and to improve our service offering. Specifically, they enable us to better understand how users interact with our website, help detect technical issues or errors, and inform our decisions about new features or improvements to an existing functionality. These technologies include:
Local storage - data may be stored permanently in your browser, even after you close the relevant window.
For example, we use local storage to store data for the sole purpose of collecting statistical information about visitors to our website, with a view to use this data to improve Prolific and our service offering.
Session storage - data is stored only for the duration of your visit to our website.
For example, we use session storage to distinguish between different tabs you have open. This helps us to identify which tab you have used to view pages on our website or interact with features.
We use cookies for the following purposes:
Strictly necessary cookies – these cookies are required for the operation of our website.
This might include using cookies for authentication purposes, so that we can identify you when you visit and navigate our website, or for the purposes of determining if you are logged onto our website.
We also use cookies to store your preferences in relation to the use of cookies more generally.
These cookies are always enabled because our website won’t work properly without them. You can switch off these cookies in your browser settings but you may then not be able to access all or parts of our website.
Marketing – these cookies process personal information to show you personalised or interest-based advertisements.
These services let us understand which site visitors have discovered Prolific via our marketing campaigns. Enabling them helps us understand whether our advertising is useful for prospective users, and how we can make it better.
Performance optimisation – these services help us to improve functionality and performance by tracking usage and enable us to optimise the service that our site offers.
Our service providers use cookies and those cookies may be stored on your computer, when you visit our website for the purposes, stated below.
| Who | Cookie Prefix | Purpose |
|---|---|---|
| Auth0 | auth0 | Manages user login |
| Cloudflare | __cf* | Bot protection and security |
| Datadog | _dd* | Error tracking and performance monitoring |
| Google Tag Manager | _gat* | Loads other cookies in accordance with consent |
| Orejime | orejime_consent | Records your cookie consent preferences |
| Klaro | klaro | Records your cookie consent preferences |
| Next.js | NEXT_LOCALE | Stores your chosen language so the site displays in the right language |
| Pendo | pendo, _pendo* | Powers in-product guidance and onboarding |
| Rollbar | (session/local storage) | Bug tracking and error reporting |
| Factors.ai | _fuid | Gathers additional data for lead generation and marketing analysis |
| _fbp, _fbc | Tracks ad conversions and stores the ad-click identifier for attribution | |
| AEC | Ensures requests within a browsing session are made by you, not other sites | |
| SIDCC | Builds a profile of your interests for personalised Google advertising | |
| SOCS | Records consent | |
| SSID | Allows YouTube videos to play on the website | |
| UULE | Sends approximate location to Google's servers | |
| Google DoubleClick | IDE | Ad personalisation and retargeting |
| Google Ads | _gc, _gcl_au | Tracks ad conversions and stores ad-click information for attribution |
| Google Analytics | _ga, ga, _gid, gat_gtag | Tracks pageviews and interactions for analysis |
| Hotjar | _hj, _hjSession*, _hjSessionUser* | Tracks pageviews and interactions for analysis and recognises returning visitors |
| Hubspot | __hs, hubspot, laboratory-anonymous-id, hubspotutk, __hstc, __hssc, __hssrc | Allows us to host HubSpot forms on our site and tracks conversions |
| Influ2 | R | Tracks ad impressions and engagements |
| Intercom | intercom, intercom-id-, intercom-session-, intercom-device-id-* | Identifies your device for chat sessions and keeps chat history |
| bcookie, li_gc, lidc, UserMatchHistory, AnalyticsSyncHistory, li_sugr | Marketing and ad tracking, consent storage, and retargeting | |
| Microsoft Clarity | _clck, _clsk, CLID | Session analytics and heatmaps |
| Microsoft Ads | _uetsid, _uetvid, MUID | Tracks Bing ad conversions |
| ChatGPT Ads | __obref | Stores an ad-click identifier so conversions can be attributed to ads shown in ChatGPT |
| Spotify Ads | _spotify, sp_t, sp_landing | Tracks Spotify ad conversions |
| G2 | (no named cookie — browser fingerprint) | Identifies visitors arriving from G2 |
| Lemlist | snitcher_device_id, snitcher_session, snitcher_user_traits | Website visitor tracking — recognises returning browsers and groups pageviews into a visit |
| Reddit Ads | _rdt* | Tracks ad conversions and retargeting |
| Segment | ajs | Statistics collection and user analysis |
| Snowplow | _sp, sp, _sp_id., _sp_ses., __spdt | Tracks pageviews and interactions for analysis |
| X (Twitter) | guest_id, muc_ads, personalization_id, _twpid | Tracks ad conversions |
| VWO | _vwo*, _vis_opt* | A/B testing |
You can choose which cookies we can set by clicking Manage cookie preferences at the bottom of our website and then adjusting the relevant toggles to ‘on’ (green) or ‘off’ (grey):