Paste your episode timestamps once and get every chapter format you need: a Podcasting 2.0 JSON chapters file for your RSS feed, ID3 CHAP chapter markers written straight into your MP3, and ready-to-paste YouTube chapters. Add the MP3 to mark chapters while you listen. Everything happens in your browser.
Last updated:
Accepts 0:00 Intro, 01:02:30 - Title, [12:05] Title and seconds like 95 Title. Add a web link and/or an image link after the title. You can also paste Podcasting 2.0 JSON to convert it.
Chapters
#
Start
Length
Title
Writes the chapters into the MP3's ID3v2 tag as CHAP frames plus a CTOC table of contents, so apps such as Overcast, Pocket Casts, Podcast Addict and many car stereos show them. Your existing title, artist and cover tags are kept and the audio is not re-encoded.
No MP3 added yet. Add the episode MP3 on the left to write chapters into it.
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How to use the Podcast Chapters Generator
Type or paste your timestamps, one chapter per line, such as 12:30 Interview. Add a link after the title if you like.
Add the episode MP3 (optional) to fill in the exact length, listen and press Add chapter at current time to mark new chapters.
Check the chapter table for lengths and warnings such as duplicate times or a chapter past the end.
Pick an output: Podcasting 2.0 JSON, YouTube, or MP3 (ID3 CHAP).
Copy or download the JSON or YouTube text, or press Download MP3 with chapters to save a tagged copy of your episode.
Chapter formats compared
Format
Where it lives
Supports
Best for
Podcasting 2.0 JSON
Separate file linked from the RSS feed with <podcast:chapters>
Titles, links, images, hidden (toc:false) chapters, editable after publishing
Modern podcast apps and hosts that support the Podcast Namespace
ID3v2 CHAP + CTOC
Inside the MP3's ID3 tag
Titles and links (images possible but rarely used)
Apps and players that read chapters from the file itself
YouTube description chapters
Plain text in the video or episode description
Titles only, whole seconds
Video podcasts on YouTube and descriptions on other platforms
Line format reference
Every line starts with a time, followed by the chapter title. Lines are sorted by time automatically, and blank lines or lines starting with # are ignored.
You type
Result
0:00 Intro
Chapter at 0 s titled "Intro"
1:02:30 - Q&A
Chapter at 3750 s (separators like - – — | are removed)
[12:05.5] Sponsor
Chapter at 725.5 s (brackets and decimals allowed)
95 Cold open
Chapter at 95 s
9:40 Guide https://example.com/guide
Adds a chapter link (url / WXXX)
9:40 Guide https://example.com/art.jpg
Adds a chapter image (img in JSON)
20:00 Ad break [hidden]
JSON "toc": false; left out of the ID3 table of contents
Tips for good chapters
Keep titles short (under about 40 characters) so they fit on phone and car screens.
Start the first chapter at 0:00. It is required on YouTube and avoids a blank gap in podcast apps.
Add chapters after the final edit. If you trim the audio later, every following timestamp shifts. Re-add the new MP3 to check the length.
Write ID3 chapters into the exact file you publish. Some hosts re-encode uploads, which can strip tags; if yours does, rely on the JSON chapters file.
Frequently asked questions
What are Podcasting 2.0 JSON chapters?
They are a small JSON file defined by the Podcast Namespace project. Each chapter has a startTime in seconds and a title, and can include an endTime, a web link (url), an image (img) and a toc flag. You host the file and reference it in your RSS feed with the podcast:chapters tag, and supporting apps show the chapters, links and artwork while the episode plays.
What are ID3 CHAP chapters?
The ID3v2 Chapter Frame Addendum defines CHAP frames that store a chapter's start and end time and sub-frames such as its title (TIT2) and link (WXXX), plus a CTOC frame that lists the chapters in order. Because they live inside the MP3 file itself, they work in any app that reads them, even without an RSS chapters file.
Does writing chapters re-encode or change my audio?
No. The tool only rebuilds the ID3v2 tag at the start of the file and copies the audio frames byte for byte, so sound quality and length stay exactly the same. Existing tags such as the episode title, artist and cover art are kept, and old chapter frames are replaced.
Should I use JSON chapters or ID3 chapters?
Use both if you can. JSON chapters can be updated after publishing without re-uploading audio and support images and links in modern apps. ID3 chapters are embedded in the MP3, so they also work in apps and devices that ignore the RSS chapters tag.
Why don't my YouTube chapters show up?
YouTube only creates chapters when the first timestamp is 0:00, there are at least three timestamps in ascending order, and every chapter is at least 10 seconds long. The YouTube tab checks these rules and shows what to fix.
How is the end of the last chapter determined?
From the episode length. If you add the MP3, the tool measures its exact duration from the audio frames, taking the encoder delay and padding stored in the LAME header into account. Otherwise it uses the length you type in.
Is there a limit on the number of chapters?
JSON chapters have no practical limit. In an ID3 table of contents, the entry count is a single byte, so a CTOC can list at most 255 chapters; the tool warns you if you go over that.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.