Klaviyo Migration Deep Dive

Overview

Comprehensive guide for migrating to Klaviyo from legacy APIs (v1/v2), competing ESPs (Mailchimp, SendGrid, etc.), or re-platforming with the strangler fig pattern. Covers data migration, API mapping, batch import, and post-migration validation.

This SKILL.md is the high-level workflow. The full, copy-paste code for every step lives in references/implementation.md; worked end-to-end scenarios live in references/examples.md.

Prerequisites

• Target Klaviyo account configured
• klaviyo-api SDK installed (npm install klaviyo-api)
• Source system access for data export
• Feature flag infrastructure (for gradual rollout)
• Auth: a Klaviyo private API key (pk_***) exported as KLAVIYO_PRIVATE_KEY — used by the SDK's ApiKeySession. Legacy v1/v2 calls used a public token in the request body; the current REST API uses the private key in the session header. See references/implementation.md.

Migration Types