---
title: "Post Thread Comment"
method: POST
path: "/v1/documents/{documentId}/threads/{threadId}/comments"
tags: ["Document Comments"]
---

# Post Thread Comment

`POST /v1/documents/{documentId}/threads/{threadId}/comments`

Posts a new comment to an existing thread on a document. The comment text must be non-empty and cannot exceed 10,000 characters.

## Valid Authentication Methods

**API Key Grants:**
- `DocumentEdit`

**OAuth 2.0 User Token Scopes:**
- `lucidchart.document.content`
- `lucidscale.document.content`
- `lucidspark.document.content`
- `lucid.document.content`

## Path parameters

- `documentId` string, uuid, required
- `threadId` string, required

## Request body

- PostCommentRequestBody — Request body for posting a comment to a thread.
  - `comment` string, required — The text content of the comment. Must be non-empty and at most 10,000 characters.

## Response `204`

No Content when the comment is successfully posted.

## Other responses

- `400` — Bad Request. * Comment must be non-empty. * Comment must not exceed 10,000 characters. * Comment cannot be posted to a closed thread.
- `403` — Forbidden if the app making the request does not have write permission to the document, or if the document does not exist.
- `404` — Not Found if the specified thread does not exist on the document.

---

[API](https://skmtc.net/lucid/apis/lucid-rest-api.md) · [All operations](https://skmtc.net/lucid/apis/lucid-rest-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/lucid/lucid-rest-api/revisions/6a32cb9e1aa7/schema)