Klaviyo Client API is one of 23 APIs that Klaviyo publishes on the APIs.io network, described by a machine-readable OpenAPI specification and an AsyncAPI event-driven specification.
Tagged areas include Client. The published artifact set on APIs.io includes an OpenAPI specification, API documentation, an AsyncAPI specification, an API reference, authentication docs, and rate-limit docs.
This API exposes 11 operations across 10 paths, and defines 78 schemas. It is described by OpenAPI 3.0.2, at version 2026-04-15.
Requests are made against a single base URL, https://a.klaviyo.com.
Metadata
The identity and technical contract details declared by the specification.
Authentication & Security 1
Klaviyo Client API declares
1 security scheme
for authenticating requests.
An API key is passed in the header as Authorization (Klaviyo-API-Key).
By default, every request must be authenticated.
Klaviyo-API-Key— Private key authentication for /api/ endpoints is performed by setting the Authorization header to Klaviyo-API-Key your-private-api-key For more information pl…
Paths & Operations 11
Across 10 paths, the API surfaces 11 operations — 3 GET, 8 POST. Each is listed below with its method, path, parameters, and response codes.
client
Schemas 78
The contract defines 78 schemas that model the data the API accepts and returns. The most detailed are PushTokenDeviceMetadata (12 properties), DeviceMetadata (12 properties), ProfileLocation (10 properties), PushTokenEntry (6 properties). Each schema is shown below with its type and property counts.
Specification
The full machine-readable OpenAPI contract behind this narrative.
Source
More from Klaviyo 12
Other APIs Klaviyo publishes across the network.