How to Integrate OptiMonk with Klaviyo

OptiMonk no longer asks for Klaviyo public and private API keys. As of the April 2026 help article, you authenticate with OAuth, pick a list and map fields. Older screenshots of Create Private API key are out of date. Do not paste keys.

Once this is on, a form fill on the campaign adds the person to the Klaviyo list you chose.

Connect a campaign

1. Log in at app.optimonk.com/login/en.

2. Campaigns → open the campaign.

3. Edit settings.

4. If OptiMonk already sees Klaviyo on the site, click Select on the Klaviyo suggestion. Otherwise Add new integration and pick Klaviyo.

5. Click Authenticate. You go to Klaviyo, pick the account, and review the requested permissions and authorize the connection.

6. You land back in OptiMonk. Name the integration. Next.

7. Choose the Klaviyo list the campaign should write to.

8. Map fields. Email, first name, last name, phone, coupon code, custom fields. Verify each destination identifier against the property you actually need, rather than relying on the field label alone.

9. Done, then Next.

A coupon shown on the campaign can go to Klaviyo as a custom property, which you then drop into a flow. That is the useful part for a "here is 10% off" popup.

Verify the signup, properties and subscription separately

The following worksheet is editorial guidance, not a claim of product-account testing. Use a new test address and record the campaign, page, selected Klaviyo account and destination list.

OptiMonk documents a double-opt-in option that requires confirmation before list admission. A profile existing in Klaviyo is therefore not sufficient evidence that the person has completed the intended subscription process.

Its guide also distinguishes email and phone consent. Inspect both channel states when your form collects both identifiers. Do not assume that an email subscription establishes SMS eligibility, or that a transferred phone number alone proves a message can be sent.

Diagnose the failed stage

If the lead is missing from OptiMonk, investigate the form submission first. If it exists there but not in the intended destination, inspect the selected account, saved campaign integration, list and confirmation status. If the record arrives but a property is missing, compare the source value and mapping before reconnecting the accounts.

Test any flow that uses a coupon property with the actual transferred value. A populated property does not by itself verify coupon validity or correct rendering in the email.

Record a material mapping change and repeat the controlled test. The reviewed source does not establish automatic replay of earlier failures or a complete policy for overwriting existing profile properties. Check those cases separately when they matter to your rollout.

Source reviewed September 6, 2026: OptiMonk’s Klaviyo setup and examples.

Other ESP guides: OptiMonk integrations.