---
title: "Add or upsert a contact"
method: POST
path: "/audiences/{id}/contacts"
tags: ["Contacts"]
---

# Add or upsert a contact

`POST /audiences/{id}/contacts`

## Request

- Base URL: `https://api.eusend.dev`
- URL: `https://api.eusend.dev/audiences/{id}/contacts`
- Auth: HTTP bearer

Addresses are lowercased. Adding an address already in the audience updates it rather than failing.

## Path parameters

- `id` string, uuid, required

## Request body

- CreateContactRequest
  - `email` string, email, required
  - `first_name` string
  - `last_name` string
  - `properties` object: Custom properties, available as `{{key}}` in a broadcast body. Keys are lowercase letters, digits and underscores, starting with a letter (max 40 characters, 20 properties per contact). `email`, `name`, `first_name`, `last_name` and `full_name` are built in and are rejected here.

## Response `201`

Created or updated.

- Contact
  - `id` string, uuid, required
  - `audienceId` string, uuid, required
  - `email` string, email, required
  - `firstName` string, nullable
  - `lastName` string, nullable
  - `properties` object: Custom properties, usable as `{{key}}` in a broadcast body.
  - `status` 'subscribed' | 'unsubscribed', required
  - `unsubscribedAt` string, date-time, nullable
  - `createdAt` string, date-time, required
  - `updatedAt` string, date-time, nullable

## Other responses

- `400`: The request body or query failed validation (`VALIDATION_ERROR`).
- `401`: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
- `403`: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
- `404`: No such resource on this organization (`NOT_FOUND`).
- `429`: Rate limit exceeded (`RATE_LIMITED`).
- `500`: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.

---

[API](https://skmtc.dev/eusend/apis/eusend-api.md) · [All operations](https://skmtc.dev/eusend/apis/eusend-api/llms.txt) · [OpenAPI document](https://skmtc.dev/eusend/apis/eusend-api/revisions/bec561f55488?raw)