Video Chapter Marker Tool

Straight from YouTube's own Help Center: the first timestamp must be 00:00, you need at least three timestamps listed in ascending order, and each chapter must be at least 10 seconds long. Miss any of these and YouTube silently ignores the whole list instead of showing chapters on the progress bar.

Whatever is natural — the tool finds the time wherever it sits on the line. "0:00 Intro", "Intro - 0:00", and "Intro 0:00" all work. Both M:SS and H:MM:SS are supported, and leading zeros are optional.

YouTube requires chapters in ascending order, so if you typed them out of sequence, they're automatically sorted for you — with a note telling you this happened, so you know to copy the sorted version rather than your original order.

It's left out of the result and named in a notice above the output, so nothing you typed disappears without you knowing about it.

Yes. Parsing, validation, and formatting all happen locally — nothing you type is uploaded anywhere.

Chapters only activate when the timestamp list sits in the video's description itself — pasting the same list into a pinned comment does not put chapters on the progress bar. Paste this tool's output into the description, not a comment, and double check the first line reads 0:00.

Either is accepted while you're typing notes — the tool parses both. For the final output, use M:SS for videos under an hour and H:MM:SS once a chapter passes the one-hour mark, since that's what YouTube expects; the tool formats each timestamp in whichever style matches its position in the video automatically.