---
title: "Add participants"
method: POST
path: "/api/v1/initiatives/{id}/participants"
tags: ["Initiatives"]
---

# Add participants

`POST /api/v1/initiatives/{id}/participants`

Add people to an active WhatsApp initiative. WARNING: each person added receives a real outbound WhatsApp message. Do-Not-Contact people are skipped.

## Path parameters

- `id` string, required — Initiative id.

## Request body

- object
  - `people` object[], required — The people to add. Each receives a real WhatsApp message.
    - `externalId` string, required — Stable unique identifier for this person in your system (CDP identity key).
    - `phoneNumber` string, required — Phone number in E.164 format, e.g. +5215512345678 — the WhatsApp recipient.
    - `name` string — First name.
    - `lastName` string — Last name.
    - `context` object — Per-person context values. Keys must match the initiative's context schema.

## Response `201`

Success

- object
  - `data` object[], required
    - `participantId` string, required
    - `phoneNumber` string, required
    - `status` 'ACTIVE' | 'COMPLETED' | 'STOPPED' | 'EXPIRED' | 'FAILED', required — ACTIVE (conversation may still happen), COMPLETED, STOPPED (messaging halted), EXPIRED, or FAILED.
  - `errors` object[], required
    - `index` number, required — Index of the person in the request `people` array.
    - `error` object, required
      - `code` string, required — One of: contact_suppressed, invalid_phone_number, unknown_context_key, enrollment_failed.
      - `message` string, required

## Other responses

- `400` — Validation failed or the request cannot proceed.
- `401` — Missing, malformed, or revoked API key.
- `404` — The resource does not exist in this organization.
- `409` — Conflicts with the current state (duplicates, wrong lifecycle state).
- `422` — The request is well-formed but semantically invalid.
- `429` — Rate limit exceeded — retry after `Retry-After`.
- `500` — Internal server error.
- `503` — Transient error — retry with a narrower request.

---

[API](https://skmtc.net/useboom/apis/boom-api.md) · [All operations](https://skmtc.net/useboom/apis/boom-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/useboom/boom-api/revisions/00f873e07076/schema)