Create a contact

POST/v1/audiences/{id}/contacts

Adds one person to an audience. Properties must be created first with the contact properties endpoints. An audience holds up to 50,000 contacts.

Required scope: contacts:manage

Parameters

Name	In	Description
`id`required	path	The audience id.

Request body

Field	Type
`email`required	`string`
`first_name`optional	`string`
`last_name`optional	`string`
`unsubscribed`optional	`boolean`
`properties`optional	`object`

Unknown fields are rejected, so a typo never silently does nothing.

Example

curl -X POST 'https://api.sendsend.email/v1/audiences/ID/contacts' \
  -H "Authorization: Bearer $SENDSEND_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "email": "maria@example.com",
  "first_name": "Maria",
  "properties": {
    "plan": "pro"
  }
}'

Response `201`

{
  "id": "con_Hk3v…",
  "object": "contact",
  "audience_id": "aud_7Qe2…",
  "email": "maria@example.com",
  "first_name": "Maria",
  "last_name": null,
  "unsubscribed": false,
  "properties": {
    "plan": "pro"
  },
  "created_at": "2026-10-06T15:00:00.000Z",
  "updated_at": "2026-10-06T15:00:00.000Z"
}

Errors

Status	Code	When
400	`validation_error`	The request body or parameters are invalid. The message says which field.
404	`not_found`	No such resource in this project.
409	`validation_error`	That email is already in the audience.
401	`unauthorized`	The API key is missing, invalid or revoked.
403	`forbidden`	The key does not have the scope this endpoint needs.

Every error has the same shape. See Errors.