Cut MP3s into blocks, right in your browser
Mark a section, listen to it, save it with its own name, and move on to the next one. Your audio never leaves your computer.
- Free, no sign-up
- Files stay on your device
- MP3 & WAV export
- Batch-friendly naming
Drag across the waveform to mark a block, then pull the red edges to adjust it. Keys: Space play/pause, ← → 1 s, with Shift 5 s, I / O set start and end.
Save blocks
| Saved file | Start | End | Length |
|---|
Blocks you save are listed here and marked in green on the waveform.
How to cut an MP3 in four steps
- Open your file
Drag an audio file onto the box above or click it to choose one. The waveform appears in a second or two, because the file is read on your own device.
- Mark a block
Drag across the waveform. Fine-tune the edges by pulling the red lines, by typing exact times, or with “Set start here” and “Set end here” while it plays.
- Check it by ear
Play, rewind and skip inside the block only. “Last 3 s” plays the tail so you can hear whether the cut lands in a pause.
- Save and continue
Name the file and save it. The next block is selected for you and the number in the name goes up, so a long recording turns into
part_01,part_02,part_03…
Built for splitting long audio, not just trimming one clip
Your files stay with you
Mp3Blocks has no upload step and no server that touches your audio. Decoding, cutting and MP3 encoding all run inside your browser tab, which is why it keeps working even if your connection drops after the page loads.
Listen inside the selection
The play button, the position slider and the ±1 s / ±5 s jumps are locked to the block you marked. You can scrub through a 40-second section without ever drifting into the next one.
Numbered blocks, one after another
After each save, Mp3Blocks selects the following stretch of the same length and increments the file name. In Chrome and Edge you can pick an output folder once and every block is written straight into it.
Keeps the original quality
When you open an MP3, Mp3Blocks reads its bitrate from the file header and preselects the matching export quality, so you don't lose more quality than necessary. You can still raise or lower it.
Clean edges
Optional fade in and fade out, from a 0.05-second de-click up to a 3-second musical fade, are applied when the file is written.
MP3 or WAV
Export MP3 from 96 to 320 kbps, or uncompressed 16-bit WAV when the clip is going into a video editor or a DAW and you don't want another round of compression.
What people use it for
Podcasts and interviews
Cut a two-hour recording into topic segments, pull a quote for social media, or remove a section that shouldn't go out.
Classes and lectures
Split a recorded class into one file per topic so students can find the part they need.
Audiobooks and voice memos
Break a long file into chapters with names that sort correctly in any player.
Music practice
Isolate a solo or a tricky passage and save it as its own file to loop while you practise.
Guides
Frequently asked questions
Is Mp3Blocks really free?
Yes. There is no account, no watermark and no limit on the number of files. The site is supported by advertising shown around the tool.
Are my audio files uploaded anywhere?
No. The file is read by your browser and processed in your computer's memory. Nothing is sent to Mp3Blocks or to anyone else. You can confirm it by disconnecting from the internet after the page has loaded: the cutter keeps working.
Which formats can I open?
Anything your browser can decode. MP3 and WAV work everywhere; M4A/AAC, OGG and FLAC work in current versions of Chrome, Edge and Firefox, and most of them in Safari.
Does cutting an MP3 reduce its quality?
Saving to MP3 means encoding the audio again, which always costs a little quality. Keeping the same bitrate as the original, which Mp3Blocks preselects for you, makes the difference very hard to hear. If you need zero extra loss, export as WAV.
Is there a file size or length limit?
There is no fixed limit, but your device has to hold the whole recording in memory. Files up to about an hour work well on a normal laptop. Very long recordings can be slow or fail on phones and older computers.
Why can't I choose a folder in my browser?
Saving straight into a folder uses the File System Access API, which Chrome, Edge and Opera support on desktop. In Safari and Firefox each file goes to your Downloads folder with the name you typed.
Does it work on phones?
It opens and cuts on modern phones, but the waveform is small and saving depends on the phone's browser. It is designed for a computer with a mouse or trackpad.
Can I use the cut audio commercially?
Mp3Blocks adds nothing to your files and claims no rights over them. Whether you can publish the audio depends on who owns the original recording.