---
title: "Add a label to a conversation"
method: POST
path: "/v1/inbox/conversations/{conversationId}/labels"
tags: ["Messages"]
---

# Add a label to a conversation

`POST /v1/inbox/conversations/{conversationId}/labels`

## Request

- Base URL: `https://zernio.com/api`
- URL: `https://zernio.com/api/v1/inbox/conversations/{conversationId}/labels`
- Auth: HTTP bearer

Facebook Messenger only. Applies one of the Page's custom labels to the person in this conversation (Graph `POST /{label-id}/label?user={psid}`). The id must be one of the Page's custom labels, otherwise 404 `resource_not_found`. Other platforms answer 400 `platform_not_supported`.

## Path parameters

- `conversationId` string, required

## Request body

- object
  - `accountId` string, required: Facebook social account ID
  - `labelId` string, required: Meta label id from listInboxLabels

## Response `200`

Label added

- object
  - `success` boolean

## Other responses

- `400`: Invalid body, or an account that is not Facebook (platform_not_supported), or Meta refusing for good (platform_api_error with Meta's message in platformError). A transient Meta failure answers 502
- `401`: Missing or invalid API key. `code` is `missing_credentials` when no Authorization header was sent and `invalid_credentials` when the key is unknown, revoked or expired.
- `403`: Inbox addon required
- `404`: Account or conversation not found, or the label is not one of the Page's custom labels
- `422`: No Facebook Page is selected on this account (linked_account_required); reconnect it and select the Page

## Changes

- **2026-10-25** `31e8537bec75`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/zernio/apis/zernio-api/changes/v1/inbox/conversations/:conversationId/labels/post.md)

---

[API](https://skmtc.dev/zernio/apis/zernio-api.md) - [All operations](https://skmtc.dev/zernio/apis/zernio-api/llms.txt) - [OpenAPI document](https://skmtc.dev/zernio/apis/zernio-api/revisions/870c96025f19?raw)