---
title: "Reply to a comment"
method: POST
path: "/v1/spaces/{spaceId}/comments/{threadId}/replies"
tags: ["Spaces"]
---

# Reply to a comment

`POST /v1/spaces/{spaceId}/comments/{threadId}/replies`

## Request

- Base URL: `https://api.spacefast.com`
- URL: `https://api.spacefast.com/v1/spaces/{spaceId}/comments/{threadId}/replies`
- Auth: HTTP bearer

Adds a reply to a comment thread; `mentions` notifies the people you name. Returns the reply in the same shape a thread's `comments` use.

## Path parameters

- `spaceId` string, required
- `threadId` string, required

## Request body

- object
  - `body` string, required
  - `mentions` string[]: Spacefast user ids to @mention. Each must be on the Space's team and able to open it; `GET /v1/spaces/{spaceId}/comments/mentionable` lists who qualifies. Mentioned people are notified.
  - `idempotencyKey` string

## Response `201`

Response for status 201

- object
  - `$schema` string, uri: Canonical JSON Schema URL for this response body. The server also sends it in the `Link: rel="describedby"` response header.
  - `data` object, required
    - `status` 'inserted' | 'existing', required
    - `comment` object, required
      - `attachments` object[], required
        - `id` string, required
        - `name` string, required
        - `contentType` string, required
        - `size` integer, required
        - `kind` 'screenshot' | 'image' | 'file', required
        - `crop` object
          - `x` number, required
          - `y` number, required
          - `width` number, required
          - `height` number, required
        - `url` string, nullable, required
      - `mentions` string[], required: Spacefast user ids this thread or reply @mentions.

## Other responses

- `default`: Problem details (RFC 9457). Any 4xx/5xx response is one `application/problem+json` document.

---

[API](https://skmtc.dev/spacefast/apis/spacefast-api.md) · [All operations](https://skmtc.dev/spacefast/apis/spacefast-api/llms.txt) · [OpenAPI document](https://skmtc.dev/spacefast/apis/spacefast-api/revisions/bd165bc7c983?raw)