{
"openapi": "3.0.2",
"info": {
"title": "Klaviyo API",
"version": "2026-07-15",
"description": "The Klaviyo REST API. Please visit https://developers.klaviyo.com for more details.",
"contact": {
"name": "Klaviyo Developer Experience Team",
"email": "developers@klaviyo.com",
"url": "https://developers.klaviyo.com"
},
"termsOfService": "https://www.klaviyo.com/legal/api-terms",
"license": {
"name": "License",
"url": "https://www.klaviyo.com/legal"
}
},
"servers": [
{
"url": "https://a.klaviyo.com",
"description": "Production"
}
],
"security": [
{
"Klaviyo-API-Key": []
}
],
"paths": {
"/api/campaign-message-assign-template": {
"post": {
"operationId": "assign_template_to_campaign_message",
"summary": "Assign Template to Campaign Message",
"description": "Creates a non-reusable version of the template and assigns it to the message.
*Rate limits*:
Burst: `10/s`
Steady: `150/m`\n\n**Scopes:**\n`campaigns:write`\n\n[OpenAPI Spec](https://raw.githubusercontent.com/klaviyo/openapi/main/openapi/stable/apis/assign_template_to_campaign_message.json)",
"parameters": [
{
"name": "fields[campaign-message]",
"in": "query",
"description": "For more information please visit https://developers.klaviyo.com/en/v2026-07-15/reference/api-overview#sparse-fieldsets",
"required": false,
"schema": {
"type": "array",
"items": {
"type": "string",
"enum": [
"channel",
"content",
"content.bcc_email",
"content.body",
"content.cc_email",
"content.from_email",
"content.from_label",
"content.media_url",
"content.preview_text",
"content.reply_to_email",
"content.subject",
"created_at",
"id",
"label",
"render_options",
"render_options.add_info_link",
"render_options.add_opt_out_language",
"render_options.add_org_prefix",
"render_options.shorten_links",
"send_times",
"updated_at"
]
}
},
"explode": false
},
{
"name": "revision",
"in": "header",
"description": "API endpoint revision (format: YYYY-MM-DD[.suffix])",
"required": true,
"schema": {
"type": "string",
"default": "2026-07-15"
}
}
],
"requestBody": {
"description": "Takes a reusable template, clones it, and assigns the non-reusable clone to the message.",
"required": true,
"content": {
"application/vnd.api+json": {
"schema": {
"$ref": "#/components/schemas/CampaignMessageAssignTemplateQuery"
}
}
}
},
"responses": {
"200": {
"description": "Success",
"content": {
"application/vnd.api+json": {
"schema": {
"$ref": "#/components/schemas/PostCampaignMessageResponse"
}
}
}
},
"4XX": {
"$ref": "#/components/responses/ClientError"
},
"5XX": {
"$ref": "#/components/responses/ServerError"
}
},
"tags": [
"Campaigns"
],
"x-klaviyo-operation-aliases": [
"create_campaign_message_assign_template"
],
"x-klaviyo-pre-release": "None",
"x-klaviyo-ratelimit": {
"burst": "10/s",
"steady": "150/m"
},
"x-klaviyo-scopes": [
"campaigns:write"
],
"x-klaviyo-subtag": "Messages"
}
}
},
"components": {
"responses": {
"ClientError": {
"description": "Client Error",
"content": {
"application/vnd.api+json": {
"schema": {
"type": "object",
"properties": {
"errors": {
"type": "array",
"items": {
"type": "object",
"required": [
"id",
"code",
"title",
"detail"
],
"properties": {
"id": {
"type": "string"
},
"code": {
"type": "string"
},
"title": {
"type": "string"
},
"detail": {
"type": "string"
},
"source": {
"type": "object",
"properties": {
"pointer": {
"type": "string"
},
"parameter": {
"type": "string"
}
}
}
}
}
}
},
"required": [
"errors"
]
}
}
}
},
"ServerError": {
"description": "Server Error",
"content": {
"application/vnd.api+json": {
"schema": {
"type": "object",
"properties": {
"errors": {
"type": "array",
"items": {
"type": "object",
"required": [
"id",
"code",
"title",
"detail"
],
"properties": {
"id": {
"type": "string"
},
"code": {
"type": "string"
},
"title": {
"type": "string"
},
"detail": {
"type": "string"
},
"source": {
"type": "object",
"properties": {
"pointer": {
"type": "string"
},
"parameter": {
"type": "string"
}
}
}
}
}
}
},
"required": [
"errors"
]
}
}
}
}
},
"schemas": {
"AgentHints": {
"description": "Optional hints emitted by the API for agent callers",
"type": "object",
"properties": {
"next_steps": {
"description": "Suggested follow-up actions for agents to take after this response",
"type": "array",
"items": {
"type": "string"
}
}
}
},
"CampaignEnum": {
"type": "string",
"enum": [
"campaign"
]
},
"CampaignMessageAssignTemplateQuery": {
"type": "object",
"properties": {
"data": {
"$ref": "#/components/schemas/CampaignMessageAssignTemplateQueryResourceObject"
}
},
"required": [
"data"
]
},
"CampaignMessageAssignTemplateQueryResourceObject": {
"type": "object",
"properties": {
"type": {
"$ref": "#/components/schemas/CampaignMessageEnum"
},
"id": {
"description": "The message ID to be assigned to",
"type": "string"
},
"relationships": {
"type": "object",
"properties": {
"template": {
"type": "object",
"properties": {
"data": {
"type": "object",
"properties": {
"type": {
"$ref": "#/components/schemas/TemplateEnum"
},
"id": {
"description": "The template ID to assign",
"type": "string",
"example": "RipRmi"
}
},
"required": [
"type",
"id"
]
}
}
}
},
"required": [
"template"
]
}
},
"required": [
"type",
"id",
"relationships"
]
},
"CampaignMessageEnum": {
"type": "string",
"enum": [
"campaign-message"
]
},
"EmailContentSubObject": {
"type": "object",
"properties": {
"subject": {
"description": "The subject of the message",
"type": "string",
"example": "Buy our product!",
"nullable": true
},
"preview_text": {
"description": "Preview text associated with the message",
"type": "string",
"example": "My preview text",
"nullable": true
},
"from_email": {
"description": "The email the message should be sent from",
"type": "string",
"example": "store@my-company.com",
"nullable": true
},
"from_label": {
"description": "The label associated with the from_email",
"type": "string",
"example": "My Company",
"nullable": true
},
"reply_to_email": {
"description": "Optional Reply-To email address",
"type": "string",
"example": "reply-to@my-company.com",
"nullable": true
},
"cc_email": {
"description": "Optional CC email address",
"type": "string",
"example": "cc@my-company.com",
"nullable": true
},
"bcc_email": {
"description": "Optional BCC email address",
"type": "string",
"example": "bcc@my-company.com",
"nullable": true
}
}
},
"ObjectLinks": {
"type": "object",
"properties": {
"self": {
"type": "string",
"format": "uri"
}
},
"required": [
"self"
]
},
"PostCampaignMessageResponse": {
"type": "object",
"properties": {
"data": {
"type": "object",
"properties": {
"type": {
"$ref": "#/components/schemas/CampaignMessageEnum"
},
"id": {
"description": "The message ID",
"type": "string"
},
"attributes": {
"type": "object",
"properties": {
"label": {
"description": "The label or name on the message",
"type": "string"
},
"channel": {
"description": "The channel the message is to be sent on",
"type": "string"
},
"content": {
"description": "Additional attributes relating to the content of the message",
"oneOf": [
{
"$ref": "#/components/schemas/EmailContentSubObject"
},
{
"$ref": "#/components/schemas/SMSContentSubObject"
}
]
},
"send_times": {
"description": "The list of appropriate Send Time Sub-objects associated with the message",
"type": "array",
"items": {
"$ref": "#/components/schemas/SendTimeSubObject"
},
"nullable": true
},
"render_options": {
"description": "Additional options for rendering the message",
"$ref": "#/components/schemas/RenderOptionsSubObject",
"nullable": true
},
"created_at": {
"description": "The datetime when the message was created",
"type": "string",
"format": "date-time",
"example": "2022-11-08T00:00:00+00:00",
"nullable": true
},
"updated_at": {
"description": "The datetime when the message was last updated",
"type": "string",
"format": "date-time",
"example": "2022-11-08T00:00:00+00:00",
"nullable": true
}
},
"required": [
"label",
"channel",
"content"
]
},
"relationships": {
"type": "object",
"properties": {
"campaign": {
"type": "object",
"properties": {
"data": {
"type": "object",
"properties": {
"type": {
"$ref": "#/components/schemas/CampaignEnum"
},
"id": {
"description": "The parent campaign id",
"type": "string"
}
},
"required": [
"type",
"id"
]
},
"links": {
"$ref": "#/components/schemas/RelationshipLinks"
}
}
},
"template": {
"type": "object",
"properties": {
"data": {
"type": "object",
"properties": {
"type": {
"$ref": "#/components/schemas/TemplateEnum"
},
"id": {
"description": "The associated template id",
"type": "string"
}
},
"required": [
"type",
"id"
]
},
"links": {
"$ref": "#/components/schemas/RelationshipLinks"
}
}
}
}
},
"links": {
"$ref": "#/components/schemas/ObjectLinks"
}
},
"required": [
"type",
"id",
"attributes",
"links"
]
},
"links": {
"$ref": "#/components/schemas/ObjectLinks"
},
"meta": {
"$ref": "#/components/schemas/ResponseMeta"
}
},
"required": [
"data"
]
},
"RelationshipLinks": {
"type": "object",
"properties": {
"self": {
"type": "string",
"format": "uri"
},
"related": {
"type": "string",
"format": "uri"
}
},
"required": [
"self",
"related"
]
},
"RenderOptionsSubObject": {
"type": "object",
"properties": {
"shorten_links": {
"type": "boolean",
"example": true,
"default": true,
"nullable": true
},
"add_org_prefix": {
"type": "boolean",
"example": true,
"default": true,
"nullable": true
},
"add_info_link": {
"type": "boolean",
"example": true,
"default": true,
"nullable": true
},
"add_opt_out_language": {
"type": "boolean",
"default": false,
"nullable": true
}
}
},
"ResponseMeta": {
"description": "Response-level metadata",
"type": "object",
"properties": {
"agent_hints": {
"$ref": "#/components/schemas/AgentHints"
}
}
},
"SMSContentSubObject": {
"type": "object",
"properties": {
"body": {
"description": "The message body",
"type": "string",
"example": "My preview sms",
"nullable": true
},
"media_url": {
"description": "URL for included media",
"type": "string",
"nullable": true
}
}
},
"SendTimeSubObject": {
"type": "object",
"properties": {
"datetime": {
"description": "The datetime that the message is to be sent",
"type": "string",
"format": "date-time",
"example": "2022-11-08T00:00:00+00:00"
},
"is_local": {
"description": "Whether that datetime is to be a local datetime for the recipient",
"type": "boolean"
}
},
"required": [
"datetime",
"is_local"
]
},
"TemplateEnum": {
"type": "string",
"enum": [
"template"
]
}
},
"securitySchemes": {
"Klaviyo-API-Key": {
"type": "apiKey",
"in": "header",
"name": "Authorization",
"description": "Private key authentication for /api/ endpoints is performed by setting the `Authorization` header to `Klaviyo-API-Key your-private-api-key`
For more information please visit https://developers.klaviyo.com/en/v2026-07-15/reference/api-overview#authentication",
"x-default": "Klaviyo-API-Key your-private-api-key"
}
}
},
"tags": [
{
"name": "Campaigns",
"description": "campaigns"
}
]
}