---
title: "Add a label to a topic"
method: POST
path: "/v2/topics/{topicId}/labels"
tags: ["Topics (group chats/channels/conversations)"]
---

# Add a label to a topic

`POST /v2/topics/{topicId}/labels`

## Request

- Base URL: `https://api.zenzap.co`
- URL: `https://api.zenzap.co/v2/topics/{topicId}/labels`
- Auth: one of:
  - HTTP bearer and API key in header `X-Signature`
  - OAuth 2
    - Client credentials
    - Token URL: `https://api.zenzap.co/oauth/token` scopes: `channel:write`
- TypeScript: <https://skmtc.dev/zenzap/apis/zenzap-external-integration-api/docs/v2/topics/:topicId/labels/post.ts> (a function with typed inputs; its response is checked against the schema)

Add a label to an existing topic. Labels are defined per organization — use
`GET /v2/organization/labels` to discover the available label IDs.

**Authorization:** Your API key bot must be a member of the topic (returns 404 if not).

**Validation:**
- `labelId` must be a valid UUID belonging to your organization (returns 400 "Invalid labelId" otherwise)
- A topic can carry at most 1 label (returns 400 if the cap is exceeded)

**Behavior:** Idempotent — re-adding a label already on the topic returns the current state.

## Path parameters

- `topicId` string, uuid, required

## Headers

- `X-Signature` string
- `X-Timestamp` integer

## Request body

- TopicLabelAddRequest
  - `labelId` string, uuid, required: The ID of the organization label to add to the topic. Must belong to your organization (see `GET /v2/organization/labels`).

## Response `200`

Label added successfully

- TopicLabelUpdateResponse
  - `id` string, uuid: The topic ID
  - `labels` string[]: Updated array of label IDs on the topic
  - `updatedAt` integer: Unix timestamp in milliseconds when the topic was updated

## Other responses

- `400`: Bad request - invalid input
- `401`: Unauthorized - invalid or missing API token
- `404`: Resource not found
- `500`: Internal server error

---

[API](https://skmtc.dev/zenzap/apis/zenzap-external-integration-api.md) - [All operations](https://skmtc.dev/zenzap/apis/zenzap-external-integration-api/llms.txt) - [OpenAPI document](https://skmtc.dev/zenzap/apis/zenzap-external-integration-api/revisions/37faae2c2036?raw)