---
title: "Adds a reaction to a message in Slack."
method: POST
path: "/reactMessage"
tags: ["message"]
---

# Adds a reaction to a message in Slack.

`POST /reactMessage`

Adds an emoji reaction to a specific message in a Slack channel. It requires the channel ID, message timestamp, and the name of the emoji reaction.

## Request body

- object
  - `body` object — Body of the reactMessage sls call
    - `arguments` object, required
      - `channelId` string, required — The ID of the channel where the message is. Channel IDs start with 'C'.
      - `timestamp` string, required — The timestamp of the message to react to.
      - `reaction` string, required — The name of the emoji to use for the reaction (e.g., "thumbsup").

## Response `200`

Successful response

- object
  - `ok` boolean, required — true if the request was successful.

## Other responses

- `400` — Bad request
- `500` — Server error

## Changes

- **2025-07-15** `c28a413c6b00` — 2 breaking, 3 info
  - the response property `error` became optional for the status `400`
  - the response property `error` became optional for the status `500`
  - api tag `message` added
  - removed the non-success response with the status `404`
  - …1 more
- **2025-07-10** `b883cbfe46f6` — 1 info
  - endpoint added
- **2025-06-20** `37c50ff8be3a` — 1 breaking
  - api path removed without deprecation

[Change history](https://skmtc.dev/microfox-ai/apis/slack-d/changes/reactMessage/post.md)

---

[API](https://skmtc.dev/microfox-ai/apis/slack-d.md) · [All operations](https://skmtc.dev/microfox-ai/apis/slack-d/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/microfox-ai/slack-d/revisions/cd0edf0c2cdf/schema)