API docs v1
POST /v1/brands/{brand_id}/email-sequences/{sequence_id}/steps/{step_id}/variants

Add an A/B variant to a step

scope write:outreach cost 1 RU idempotent required

Add an A/B variant to one email step: another template, subject or body, and the share of the step's contacts that get it. The step needs a template first, and the step's variants sum to 100 percent at most. Requires the editor role and the brand owner on Pro.

Path parameters

Query parameters

  • dry_run boolean optional

    Preview the call without executing it. Runs auth, scope, eligibility and body validation, then returns 200 with a dry_run object reporting the request-unit and credit cost plus a non-consuming quota snapshot. Nothing is debited, reserved, dispatched or mutated. An invalid body still returns 422.

    default: false

Header parameters

  • Idempotency-Key string required

    Required with an API key, else 400 idempotency_key_required: a new value per operation (a UUID works). A retry with the same key and body within 24 hours replays the first response instead of running again. Ignored with dry_run=true.

Request body

application/json required
Type: EmailVariantCreate
  • template_id string required

    The template it sends: the step's own when only the subject changes.

  • variant_name string required

    Name, unique in the step.

    min length: 1 · max length: 100

  • body_override string (nullable) nullable

    Its own HTML body.

  • subject_override string (nullable) nullable

    Its own subject.

  • traffic_percentage integer

    Share of the step's contacts, in percent; the step's variants sum to 100 at most.

    min: 1 · max: 100 · default: `50`

Example payload 
{
  "subject_override": "Quick question about {{page_title}}",
  "template_id": "2b3c4d5e-6f70-4a1b-8c2d-3e4f5a6b7c8d",
  "traffic_percentage": 50,
  "variant_name": "B"
}

Responses

Add an A/B variant to a step application/json
Type: EmailVariant
  • id string required

    Variant id.

  • is_winner boolean required

    Declared the winner: it now gets all of the step's contacts.

  • sequence_id string required

    The sequence.

  • step_id string required

    The email step it varies.

  • traffic_percentage integer required

    Share of the step's contacts it gets, in percent.

    min: 1 · max: 100

  • variant_name string required

    Name, e.g. B.

  • body_override string (nullable) nullable

    Its own HTML body.

  • created_at string (nullable) nullable

    When the variant was created.

    format: `date-time`

  • object string

    default: `email_variant`

  • results EmailVariantResults (nullable) nullable

    How it performs; on the list only, null on a write.

  • subject_override string (nullable) nullable

    Its own subject.

  • template_id string (nullable) nullable

    The template it sends.

  • updated_at string (nullable) nullable

    Last change.

    format: `date-time`

  • winner_declared_at string (nullable) nullable

    When it was declared the winner.

    format: `date-time`

Example response 
{
  "created_at": "2026-09-20T10:00:00+00:00",
  "id": "6f708192-a3b4-4c5d-8e6f-7a8b9c0d1e2f",
  "is_winner": false,
  "object": "email_variant",
  "results": {
    "bounced": 0,
    "open_rate": 60,
    "opened": 6,
    "replied": 2,
    "reply_rate": 20,
    "sent": 10
  },
  "sequence_id": "4d5e6f70-8192-4a3b-9c4d-5e6f7a8b9c0d",
  "step_id": "s1",
  "subject_override": "Quick question about {{page_title}}",
  "template_id": "2b3c4d5e-6f70-4a1b-8c2d-3e4f5a6b7c8d",
  "traffic_percentage": 50,
  "updated_at": "2026-09-20T10:00:00+00:00",
  "variant_name": "B"
}
Request validation failed application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "validation_error",
    "message": "Request validation failed"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
Missing or invalid credentials application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "unauthorized",
    "message": "Missing or invalid credentials"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
You do not have permission to access this resource application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "forbidden",
    "message": "You do not have permission to access this resource"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
Resource not found application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "not_found",
    "message": "Resource not found"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
Resource conflict application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "conflict",
    "message": "Resource conflict"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
Request body did not match the expected schema application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "body_validation_error",
    "message": "Request body did not match the expected schema"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
Per-minute rate limit exceeded application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Per-minute rate limit exceeded"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
An unexpected error occurred application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "internal_error",
    "message": "An unexpected error occurred"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}
Service temporarily unavailable, please retry application/json
Type: ApiError
  • error object required
    Show fields
    • code string required

      Stable machine-readable error code from the catalog.

    • message string required

      Human-readable description suitable for logging.

    • details object

      Optional, code-specific context (e.g. errors array for validation_error, retry_after for service_unavailable). Shape depends on error.code; treat as opaque otherwise.

      Show fields

      Empty object (no properties).

  • request_id string

    Server-generated correlation id for the request. Mirrors the X-Correlation-ID response header. Include this when contacting support.

    format: `uuid`

Example response 
{
  "error": {
    "code": "service_unavailable",
    "message": "Service temporarily unavailable, please retry"
  },
  "request_id": "9f6c4e8a-1d3b-4c8b-9f1e-7a3b1c2d3e4f"
}