# OptiMonk Cookies Canonical URL: https://support.optimonk.com/en/articles/optimonk-cookies An HTTP cookie is a small piece of data stored on the user's computer by the web browser while browsing a website. Each time the same computer requests a page with a browser, it will send the cookie, too. Cookies are used to identify specific users and improve your web browsing experience. The cookies below are written by the OptiMonk script on **your** site — the same script serves campaigns you build here and campaigns that live in the classic admin. Which of them a visitor actually gets depends on what is running on the domain; the last column of the summary table says so. --- ## 1. optimonkClient This cookie is created during a visitor's first visit and helps store information needed for campaigns. - **Visitor data** includes the timestamp of the first visit, the timestamp of the last visit, and the number of pages viewed. - **Campaign data** includes when the campaign started, its current status, and the status of a sticky teaser if one is set for the campaign. - **Unique visitor identification** is based on the **optimonkClient** cookie. A visitor may be counted multiple times as a unique visitor if the cookie is deleted or not stored. This can happen if the user does not give their consent to storing cookies, or deletes browser cookies. - The last visit time and the number of page views are updated with every visit. Each visit cookie expires after one year. **Teaser state:** the sticky teaser — the small tab that reopens a closed campaign — is a classic-admin feature. Campaigns built in this app are shown as a **card** (a centered popup over a dimmed background) or **fullscreen**, with no teaser, so no teaser state is stored for them. ## 2. optiMonkClientId This cookie serves as a **unique visitor identifier**, which is also used for visitor count reporting. - It is created on the first visit and remains the same. - It is used for tracking purposes to associate incoming data with a specific visitor (for example, identifying which events a visitor interacted with). - This cookie expires after one year. ## 3. omLastFilled This cookie stores information about the last time a campaign was filled out and which variant was submitted. - It records the timestamp of the submission and the creative (variant) that was filled in. ## 4. omAbTest[number] This cookie is used for popup A/B testing and stores the variant assigned to the visitor. It ensures that visitors consistently see the same variant across their sessions, maintaining a seamless and reliable testing experience. - The **campaign ID** replaces the `[number]` in the cookie name. - This one is in use for campaigns built here as well: when a campaign has more than one variant — a duplicate, an AI tweak, an adopted concept, or a **control** arm that shows nothing — traffic is split between them by their traffic weights, and this cookie is what keeps a returning visitor on the same arm. ## 5. optiMonkSession This cookie stores the **Session ID**, representing the visitor's current session. - It records the timestamp of when the session started. - The cookie expires at the end of the session. ## 6. optiMonkExperiments_[experiment id] This cookie stores data for multi-campaign A/B tests. - It is created only if at least one active multi-campaign A/B test is on the site. - This cookie expires after one year. - Multi-campaign experiments are set up in the classic OptiMonk admin. A campaign built in this app is never part of one, so this cookie appears only if your domain also runs classic-admin experiments. ## 7. OptiMonkSmartAbTest_[number] This cookie determines which version to display for Smart A/B tests. The `[number]` in the cookie name represents the campaign ID. - Smart A/B testing is also a classic-admin feature — the same caveat as above applies. --- ## Summary | Cookie | Purpose | Expires | Set for | | --- | --- | --- | --- | | optimonkClient | Visitor and campaign state | 1 year | Every campaign (teaser state: classic admin only) | | optiMonkClientId | Unique visitor identifier | 1 year | Every campaign | | omLastFilled | Last submission + variant | — | Every campaign | | omAbTest[campaign id] | A/B variant assignment | — | Campaigns with more than one variant, built here or in the classic admin | | optiMonkSession | Session identifier | End of session | Every campaign | | optiMonkExperiments_[experiment id] | Multi-campaign A/B test | 1 year | Classic-admin experiments only | | OptiMonkSmartAbTest_[campaign id] | Smart A/B test | — | Classic-admin Smart A/B only | --- ## Data storage Personal information, such as IP addresses, is only stored for up to 14 days. The entered data from our input fields (such as email address, First Name, Last Name, and phone number) is securely stored on servers located in Frankfurt, Germany. These servers use an encrypted connection and restricted ports to ensure data protection. You might also want to check our [Privacy Policy](https://www.optimonk.com/privacy-policy) for further information. --- ## Targeting on your own cookies These are the cookies OptiMonk sets. If you want to *read* a cookie of your own and decide who sees a campaign based on it, that is a targeting rule: the campaign's **Settings** tab → **Who should see the popup** → **Add new rule** → **Cookie segmentation**.