Answer
Why doesn't Klaviyo identify all my returning visitors?
Klaviyo recognizes a returning visitor through a browser cookie or an identifying action such as an email click. It can miss people when the browser has shortened or deleted the cookie, when they come back on a new device or browser, or when they've never given the brand their details. Klaviyo's Extended ID and First-Party ID help with the first case, so start there.
October 31, 2026
Klaviyo can miss a returning visitor when the browser has shortened or deleted its cookie, when the person comes back on a new device or browser, or when Klaviyo has no profile for them. Klaviyo misses some visitors for each of these reasons, and each has a different remedy.
What causes each miss?
| Cause | What happens | What helps |
|---|---|---|
| The browser limits the cookie | __kla_id is set by JavaScript for 2 years, but browsers can shorten that. Safari deletes it after 7 days of browser use without interaction with the site. |
Extended ID and First-Party ID |
| A new device or browser | Cookies don't cross devices, so that browser starts unknown. | An email click or store login |
| No profile exists | The visitor has never shared their details with your brand. | A signup or purchase |
Which of these can you fix first?
Start with the cookie limit. Read Klaviyo's Extended ID and First-Party ID and turn on the free option. Extended ID is on all Klaviyo plans. First-Party ID sets a server cookie that restores __kla_id, though it identifies only people who already have a profile. How long cookies last in Safari covers the exceptions.
These options work within one browser. A person who shopped on a laptop and arrives on a phone is new to that phone until an email click or login identifies them. Device recognition explains why knowing a device and knowing a person are separate problems.
Does recognizing someone fix what they see?
Recognition decides whether Klaviyo can act on a visit. It doesn't decide what the shopper finds when they arrive. Someone can be correctly identified, get your cart email on time, click it on a phone and still reach an empty cart.
What does reOtter do differently?
reOtter recognizes people who've already given your brand their details, without a third-party network, in a record that doesn't depend on a browser cookie surviving. It uses that recognition on your site. The cart recovery page restores a cart when reOtter holds it and knows who clicked, and the returning customer widget shows recognized customers their usuals or due items on any page without a login. The widget is a paid feature and is frequency-capped.
Strangers aren't identified, and there's no shared identity network. Your brand's Klaviyo keeps sending your emails and deciding who gets them.
Key takeaways
- Klaviyo misses some returning visitors because of browser cookie limits, new devices or missing profiles.
- Turn on Extended ID first, since it's available on every Klaviyo plan.
- Recognizing a shopper and showing them the right page are separate jobs, and both matter.
See how reOtter restores the cart → Abandoned cart recovery
Frequently asked questions
- How many returning visitors does Klaviyo miss?
- It varies by store, browser mix and setup, so a general figure may not describe your store. Klaviyo's own options can improve recognition. Compare your numbers before and after a change instead of relying on a general estimate.
- Should I buy an identity tool before using Klaviyo's options?
- Turn on Klaviyo's options first. Extended ID is on all Klaviyo plans, free and paid. After that you can judge whether a further tool is worth it for your store.
- Can Klaviyo identify a visitor who has never shared their details?
- First-Party ID won't help here, because Klaviyo says it identifies only people with an existing profile. Naming strangers is the territory of website visitor identification vendors. Those vendors match visitors against shared cross-brand graphs, which is a different approach with different trade-offs.
- Does reOtter send Klaviyo's cart emails to more people?
- It doesn't. reOtter recognizes returning customers for what they see on your site, and your brand's Klaviyo still decides who gets its flows. reOtter also makes no claim to recognize more people than any vendor.