> ## Documentation Index
> Fetch the complete documentation index at: https://www.tella.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Chapters

> Read and replace a video's chapter markers.

Chapter timestamps use seconds on the final video timeline. Chapter IDs are not stable, so chapter updates always replace the complete list rather than targeting individual chapters.

## get\_chapters

Get every chapter on a video, ordered by timestamp.

<ParamField path="videoId" type="string" required>
  Video ID
</ParamField>

## set\_chapters

Replace every chapter on a video. Timestamps must be non-negative, ascending, and within the video duration. Pass an empty `chapters` array to clear all chapters.

<ParamField path="videoId" type="string" required>
  Video ID
</ParamField>

<ParamField path="chapters" type="object[]" required>
  Complete replacement array of `{timestampSeconds, title, description}` objects

  <Expandable title="properties">
    <ParamField path="timestampSeconds" type="integer" required>
      Chapter start time in whole seconds on the final video timeline.
    </ParamField>

    <ParamField path="title" type="string" required>
      Single-line chapter title
    </ParamField>

    <ParamField path="description" type="string" required>
      Chapter description. Use an empty string when omitted. Lines formatted like a timestamp followed by a title are not allowed.
    </ParamField>
  </Expandable>
</ParamField>


## Related topics

- [Chapters](/docs/help/editing/chapters.md)
- [Get video chapters](/docs/api-reference/videos/get-video-chapters.md)
- [Replace video chapters](/docs/api-reference/videos/replace-video-chapters.md)
- [YouTube chapters](/docs/help/export-videos/youtube-chapters.md)
- [Product Changelog](/docs/changelog.md)