Chapter Marker Formatter
Validate and format YouTube chapter markers: 00:00 start, ascending times, at least 3 chapters. With correction suggestions.
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The result will appear here …
Validate and format YouTube chapter markers
Paste your chapter list, for example 00:00 Intro, 01:30 Prep, 05:12 Result. The formatter checks the YouTube rules: the first chapter must start at 00:00, times must ascend, at least three chapters are required and each chapter needs at least 10 seconds. Violated rules are listed with correction suggestions.
Accepted corrections flow into the finished block that you copy and paste into the YouTube description. Optionally enter the video length, then the formatter also checks whether the last chapter runs past the end of the video. Everything runs locally in the browser.
Frequently asked questions
Why must the first chapter start at 00:00?
YouTube only enables chapters when the first marker sits exactly at 00:00. If it starts later, the player shows no chapters even though the list looks correct. The formatter detects this and suggests the fix.
How many chapters does a video need at minimum?
Three. With fewer than three chapters YouTube shows no chapter bar. Also each chapter must last at least 10 seconds, otherwise the marker is ignored.
Can the formatter repair my list automatically?
It suggests corrections, for example moving the start to 00:00 or sorting duplicate times. You review each suggestion and accept it individually. That keeps you in control of your chapters.