Klaviyo

The API v2 and v3 cover profiles, events, metrics, campaigns, flows, lists/segments, and templates. The profile and event tracking endpoints are the primary agent integration surfaces — agents can identify customers, track behavioral events, and update profile properties that drive Klaviyo's segmentation and flow logic. That enables agents to be the source of behavioral truth that powers Klaviyo's marketing automation without manual data synchronization.

Reliability is production-grade for marketing infrastructure at scale. Klaviyo handles high-volume event ingestion for large e-commerce operations. Event tracking should be treated as eventually consistent — events are ingested asynchronously, and flow triggers based on events may have brief processing delays. Teams building real-time behavioral triggers should validate the actual latency between event tracking and flow execution in their Klaviyo environment.

Klaviyo is the dominant email and SMS marketing platform for e-commerce, with a particularly strong API designed for event-driven marketing automation. For agents in e-commerce contexts, Klaviyo's profile and event tracking APIs enable behavioral marketing automation — triggering personalized email flows based on purchase events, cart abandonment, browsing behavior, and custom events. The deep Shopify integration reflects its e-commerce positioning; it is less suited to B2B or non-commerce marketing automation.

Authentication uses private API keys for server-to-server access and public keys for client-side event tracking. The private key provides full API access for agent workflows; teams should store it as a server-side secret and never expose it in client-side code. Klaviyo has introduced API key scoping to limit access by resource type, which is worth using for agents with limited data access requirements.

Documentation is comprehensive and well-maintained. The API reference is thorough, and the guides for e-commerce integration patterns are particularly useful. Teams migrating from older Klaviyo API versions to v3 should read the migration guides carefully, as the v3 API has a different data model for several resources.