Developer's Guide: Data API Protocol – Comments

A comment is a text response to a video. Logged-in users can add comments to a video but cannot modify or delete those comments. In addition, please note that YouTube will convert any HTML markup that appears in a comment into plain text. Typically, a user would add a comment to a video after watching that video.

This page contains the following sections:

Retrieving comments for a video

Each video entry contains a <gd:comments> tag, which encapsulates the URL to which you will send API requests to retrieve or append to the list of comments for the video. The sample XML below shows how this URL appears in an API response:

<feed>
  <entry>
    ...
    <media:group>
      ...
    </media:group>
    <gd:comments>
      <gd:feedLink
        href='http://gdata.youtube.com/feeds/api/videos/VIDEO_ID/comments'/>
    </gd:comments>
  </entry>
</feed>

Each comment has an author, a title and content. The following XML shows a sample API response containing a comments feed:

<?xml version='1.0' encoding='UTF-8'?>
<feed xmlns='http://www.w3.org/2005/Atom'
  xmlns:openSearch='http://a9.com/-/spec/opensearch/1.1/'
  xmlns:batch='http://schemas.google.com/gdata/batch'
  xmlns:yt='http://gdata.youtube.com/schemas/2007'
  xmlns:gd='http://schemas.google.com/g/2005'
  gd:etag='W/&quot;DE8HQXo-eip7ImA9WxRQGU4.&quot;'>
  <id>tag:youtube,2008:video:ZTUVgYoeN_b:comments</id>
  <updated>2008-07-18T22:10:57.065Z</updated>
  <category scheme='http://schemas.google.com/g/2005#kind'
    term='http://gdata.youtube.com/schemas/2007#comment'/>
  <title>Comments on 'My Walk with Mr. Darcy'</title>
  <logo>http://www.youtube.com/img/pic_youtubelogo_123x63.gif</logo>
  <link rel='related' type='application/atom+xml'
    href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b?v=2'/>
  <link rel='alternate' type='text/html'
    href='http://www.youtube.com/watch?v=ZTUVgYoeN_b'/>
  <link rel='http://schemas.google.com/g/2005#feed'
    type='application/atom+xml'
    href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b/comments?v=2'/>
  <link rel='http://schemas.google.com/g/2005#post'
    type='application/atom+xml'
    href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b/comments?v=2'/>
  <link rel='http://schemas.google.com/g/2005#batch'
    type='application/atom+xml'
    href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b/comments/batch?v=2'/>
  <link rel='self' type='application/atom+xml'
    href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b/comments?...'/>
  <link rel='service' type='application/atomsvc+xml'
    href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b/comments?alt=atom-service&v=2'/>
  <link rel='next' type='application/atom+xml'
    href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b/comments?...'/>
  <author>
    <name>YouTube</name>
    <uri>http://www.youtube.com/</uri>
  </author>
  <generator version='2.0'
    uri='http://gdata.youtube.com/'>YouTube data API</generator>
  <openSearch:totalResults>9051</openSearch:totalResults>
  <openSearch:startIndex>1</openSearch:startIndex>
  <openSearch:itemsPerPage>25</openSearch:itemsPerPage>
  <entry gd:etag='W/&quot;D0YASX47eCp7ImA9WxRQGU8.&quot;'>
    <id>tag:youtube,2008:video:xpI6VNvRTII:comment:F53EAC190E4EA5C9</id>
    <published>2008-07-18T14:57:59.000-07:00</published>
    <updated>2008-07-18T14:57:59.000-07:00</updated>
    <category scheme='http://schemas.google.com/g/2005#kind'
      term='http://gdata.youtube.com/schemas/2007#comment'/>
    <title>Walking is fun</title>
    <content>I like it a lot.</content>
    <link rel='related' type='application/atom+xml'
      href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b?v=2'/>
    <link rel='alternate' type='text/html'
      href='http://www.youtube.com/watch?v=ZTUVgYoeN_b'/>
    <link rel='self' type='application/atom+xml'
      href='http://gdata.youtube.com/feeds/api/videos/ZTUVgYoeN_b/comments/F53EAC190E4EA5C9?v=2'/>
    <author>
      <name>andyland74</name>
      <uri>http://gdata.youtube.com/feeds/api/users/andyland74</uri>
    </author>
  </entry>
  <entry>
    ...
  </entry>
  ...
</feed>

Identifying comments that are replies to other comments

YouTube users may respond to a comment with another comment. When displaying these comments, you may want to indent comments that reply to other comments to identify comment threads. You could also link comments that reply to other comments to help users to follow a comment thread. In an XML response, a comment that was posted in response to another comment will contain an in-reply-to link as shown in the following <link> tag:

<link rel="http://gdata.youtube.com/schemas/2007#in-reply-to"
  type="application/atom+xml" 
  href="http://gdata.youtube.com/feeds/api/videos/2cd.../comments/978..."/>

Adding a comment in response to a video

To add a comment to a video, send an HTTP POST request to the URL identified in the <gd:feedLink> tag that appears inside the <gd:comments> tag. The actual comment that you are submitting appears as the value of the <content> tag in the XML that constitutes the body of the POST request.

The sample XML API request below demonstrates how to add a comment to a video.

POST /feeds/api/videos/VIDEO_ID/comments HTTP/1.1
Host: gdata.youtube.com
Content-Type: application/atom+xml
Content-Length: CONTENT_LENGTH
Authorization: AuthSub token="AUTHORIZATION_TOKEN"
GData-Version: 2
X-GData-Client: CLIENT_ID
X-GData-Key: key=DEVELOPER_KEY

<?xml version="1.0" encoding="UTF-8"?>
<entry xmlns="http://www.w3.org/2005/Atom"
    xmlns:yt="http://gdata.youtube.com/schemas/2007">
  <content>This is a crazy video.</content>
</entry>

Adding a comment in reply to another comment

The API request for adding a comment in response to a video is nearly identical to the API request for adding a comment in reply to another comment. The only difference is that the latter request contains an additional <link> tag that identifies the comment being replied to. The following instructions explain how to format the <link> tag:

1. Set the rel attribute value to http://gdata.youtube.com/schemas/2007#in-reply-to.
2. Set the type attribute value to application/atom+xml.
3. Set the href attribute value to the self link for the comment being replied to.

The sample XML API request below demonstrates how to add a comment in reply to another comment. The <link> tag that indicates that the comment is a reply to another comment is highlighted in bold text.

POST /feeds/api/videos/VIDEO_ID/comments HTTP/1.1
Host: gdata.youtube.com
Content-Type: application/atom+xml
Content-Length: CONTENT_LENGTH
Authorization: AuthSub token="AUTHORIZATION_TOKEN"
GData-Version: 2
X-GData-Client: CLIENT_ID
X-GData-Key: key=DEVELOPER_KEY

<?xml version="1.0" encoding="UTF-8"?>
<entry xmlns="http://www.w3.org/2005/Atom"
    xmlns:yt="http://gdata.youtube.com/schemas/2007">
  <link rel="http://gdata.youtube.com/schemas/2007#in-reply-to"
    type="application/atom+xml" 
    href="http://gdata.youtube.com/feeds/api/videos/VIDEO_ID/comments/COMMENT_ID"/>
  <content>This is a comment about another comment.</content>
</entry>

Note: The POST URL for this API request specifies the video associated with the new comment. The <link> tag identifies the original comment to which the new comment replies. The new comment and the original comment must be associated with the same video.