Check and format YouTube chapter timestamps

The four rules, and what the tool says about each

• The first timestamp is 0:00. If your list starts later, the tool tells you, and the option “Add 0:00 Intro” puts a first chapter in for you.
• At least three timestamps. Two chapters are not enough for YouTube to show a chapter list.
• Ascending order. A time that comes before the one above it is reported by line number. “Sort the list by time” fixes the order if the times themselves are right.
• At least ten seconds each. A chapter lasts until the next timestamp, so two stamps eight seconds apart make the first chapter too short. If you enter the video's length, the last chapter is checked against the end as well.

An example

Pasted:
0:00 Welcome
0:45 Why subtitles break
- 3:10 - Fixing timing
Questions from the chat 5:02
5:08 Wrap-up

Result:
Line 4: "Questions from the chat" lasts 6 s. Chapters must be at least 10 seconds.

The list reads fine to a person, but the “Questions” chapter is six seconds long, so YouTube would not make chapters from it. Merge it into the wrap-up, move the time, or give it more room, and the list passes.

Tidying

Whatever style the list arrived in (a dash before the time, the time after the title, brackets, bullets) comes out as one tidy line per chapter with the time first, the way a description is usually written. If any chapter is an hour in or later, every time is written with hours, so the list stays consistent. Titles are kept exactly as you wrote them apart from extra spaces.

Finding the chapter points

The slow part of chapters is deciding where they go. A transcript with a timestamp on every line makes that quick: skim for the places the speaker changes subject, and copy the times. With a Scriptorium transcript you can also search for a phrase and see the time it was said. If you paste a transcript that has times on every line and want the words alone, use remove timestamps, and for captions as well as chapters see subtitles for YouTubers.

Writing chapter titles that work

A chapter title appears in the player's progress bar and in the list under the video, so it has to make sense on its own and fit on one line. Say what the section is about rather than what happens in it (“Fixing subtitle timing” rather than “Next part”), keep it short, and avoid starting two chapters with the same words. A viewer scanning the list should be able to tell the sections apart.

What this tool does not do

It does not connect to YouTube, look at your video or guess chapters. It runs in the page, on the text you paste, and it checks against the rules YouTube publishes for chapters that you write yourself. Automatic chapters that YouTube generates are YouTube's own feature and are not touched by anything here.