Download the file and run ffmpeg -i input.mp4 -i chapters.ffmetadata.txt -map_metadata 1 -codec copy output.mp4 to add the chapters without re-encoding.
How to make chapters
While you edit or rewatch the video, note the time each new section starts and give it a short, descriptive title. Paste the list into the box on the left. ChapterStamp understands timestamps at the start or end of a line, in brackets, after bullets and separated by dashes or colons, so notes copied from an editor, a spreadsheet or a transcript usually work as they are. Press Clean up & sort to rewrite them in one consistent style.
Enter the video length to check the final chapter too and to give WebVTT and FFmpeg exports a correct end time. If you add a five-second intro after writing your notes, set Shift to 5 and press Shift all: every timestamp except 0:00 moves later by five seconds.
The YouTube chapter rules
YouTube only creates chapters when the list in your description meets three conditions. The first timestamp is 0:00. There are at least three timestamps. Each chapter is at least ten seconds long. ChapterStamp checks all three, highlights short chapters in red in the table, and warns about duplicate start times or timestamps past the end of the video. Good chapter titles are short and specific, such as “Installing the app” rather than “Part 2”, because they appear on the progress bar and in search.
Export formats
YouTube description text is plain timestamps and titles. Podcasting 2.0 JSON is the chapters file used by podcast hosts and apps. WebVTT is the track format for HTML5 players and many course platforms. FFmpeg metadata embeds chapters in MP4, M4A, M4B and MKV files. CSV opens in a spreadsheet, and Markdown makes tidy show notes.
Private by design
ChapterStamp has no accounts and no server-side processing. Your timestamps are parsed in this browser and the last list is saved in local storage on this device only.
Frequently asked questions
Does this re-encode my video?
No. With -codec copy FFmpeg only rewrites the container metadata.
Does it work for audiobooks?
Yes. M4B audiobooks use the same chapter metadata.
Are special characters escaped?
Yes. Equals signs, semicolons, hashes and backslashes in titles are escaped as FFmpeg requires.
Is ChapterStamp free?
Yes. Formatting, checking and exporting chapters is free with no sign-up.
Is my text uploaded?
No. Everything runs in your browser and your last list is saved only on this device.