A free MP3 editor in your browser: cut, fade and normalise audio

What this audio editor is, and is not

Free audio editing software usually means a large program with tracks, plugins and a steep learning curve. If you only need to edit an MP3, cut a song, trim a voice recording or make a quiet file louder, that is far more than the job needs.

The audio editor is a simple waveform editor. You open a file, drag across the part you care about, and press a button. It opens MP3, WAV, M4A, AAC, OGG and FLAC files, and it can also open a video so you can work on its soundtrack. It runs in your browser, so the audio is never uploaded, and it is free with no account and no watermark.

What it does not do: there are no multiple tracks, no mixing of separate files, no plugins or effects such as reverb or equalisers, no pitch changes and no noise-removal filter. It edits one recording at a time. For the tasks below, that is plenty.

How to edit an MP3 file, step by step

1. Open the editor and drop in your MP3, or any audio or video file.
2. Drag across the waveform to select a section, or type exact start and end times such as 1:05.25.
3. Apply an edit: Cut, Keep only, Silence, a fade, or a volume change. Use Play selection and Loop to listen first.
4. Export as MP3, M4A or WAV and download.

Every edit can be undone with the undo and redo buttons or Ctrl+Z and Ctrl+Shift+Z (Command on a Mac). Several steps are kept; very long recordings keep fewer to save memory.

Cut, trim and crop audio

Cutting is the most common job, whether you search for a music cutter, a song cutter or an online audio cutting tool. There are two buttons that matter:

• Keep only throws away everything outside your selection. It is the quickest way to trim the ends of a recording or pull out the part of a song you want.
• Cut removes the selection and closes the gap. Use it to remove a mistake, a cough or a tangent from the middle.
• Silence mutes the selection without changing the length, which matters if the audio has to stay in sync with something else.

Each cut gets a 5-millisecond fade on both sides of the join. That is too short to hear as a fade, but long enough to prevent the click you would otherwise get from a sudden jump in the waveform.

Fade in, fade out and change the volume

Fade in and Fade out use an equal-power curve over your selection. With nothing selected, they fade the first or last three seconds, which is exactly what you want for the end of a song or the start of a voice-over. Select a longer part for a slower fade.

Volume raises or lowers the selection, or the whole file, by up to 20 dB with smooth edges, so you can lift one quiet passage without touching the rest. Be careful when raising levels: if a loud part is already near the top, making it louder only distorts it.

Remove long pauses

Interviews, voice notes and lectures often have gaps that make them drag. Remove pauses finds stretches that are quieter than the rest of the recording and last longer than the length you choose, then cuts them while keeping a short breathing space so speech still sounds natural. One second is a good start for voice recordings. Go shorter for a punchier feel.

If the audio belongs to a video and you want the pauses cut from the picture too, the silence remover works on the video itself, and removing pauses from talking videos covers the settings that sound natural.

Normalise loudness

Normalising raises or lowers a whole recording until it reaches a target loudness, so it does not sound much quieter or louder than what plays before and after it. Loudness here is measured in LUFS, which tracks how loud audio sounds over its whole length, not just its highest peak.

• Minus 14 LUFS, a common reference for YouTube, Spotify and other streaming platforms.
• Minus 16 LUFS, widely used for podcasts and spoken word.
• Minus 19 LUFS, gentler, for quiet voice recordings that should not be pushed hard.
• Minus 23 LUFS, the EBU R128 broadcast standard.

The editor measures integrated loudness and true peak, applies the gain needed to reach the target, and then a limiter keeps true peaks under minus 1.5 dBTP so the file does not distort if a platform converts it again. For a fuller report, including loudness range, use the loudness meter. The reasoning behind the targets is in LUFS for YouTube, Spotify and podcasts.

Choosing the format you save

• MP3 (128 to 320 kbps) plays everywhere. 192 kbps is transparent for most listeners, and 128 kbps is fine for speech.
• M4A (AAC) (128 to 256 kbps) sounds better than MP3 at the same bitrate and is the native format on Apple devices.
• WAV (16 or 24-bit) is uncompressed, best for handing to someone else to edit. Choose 24-bit for the most headroom.

One honest point about MP3 editing: MP3 is a lossy format, so opening an MP3, editing it and saving another MP3 re-compresses the audio. At a high bitrate such as 192 or 320 kbps the difference is hard to hear, but if you will edit many times, work from a WAV and save the MP3 once at the end. Recording it yourself? The voice recorder can save a WAV for exactly that.

To change format without editing anything, or to convert a whole folder, use the audio converter. To save the soundtrack of a video as audio, use Extract Audio, and see extract audio from a video for the format and bitrate to pick. Putting a whole episode together? Make a podcast in one browser tab lays these edits out in order.

Editing audio on a phone

The editor runs in the browser, so there is no app to install. Long recordings are held in memory while you edit, and an hour of stereo audio needs over a gigabyte, so for very long files a computer is more comfortable.