How to master a song online
- Load your final mix. WAV, MP3, FLAC, M4A and OGG files work. The file is read on your device and never uploaded.
- Pick a style. Balanced suits most songs. Warm, Bright and Punchy color the sound in a clear direction.
- Choose the intensity. Low keeps your mix close to how it is, High makes bigger changes to tone, glue and width.
- Set the loudness. Streaming (−14 LUFS) is right for YouTube, Spotify and Apple Music. Loud and Max are for DJ sets, clubs and places that don’t even out volume.
- Compare and download. Switch between Original and Mastered with Same volume on, so you judge the sound and not just the level. Then download a WAV or MP3.
What the tool does to your song
Tone
The tool measures how much energy your song has in each octave, from the deep bass to the air above 10 kHz, and compares it with the average balance of modern commercial mixes. It then nudges each band part of the way toward that balance. A muddy mix loses a little low mid, a dull one gets more presence. The style adds its own color on top, and the chart under the player shows exactly what changed.
Glue
A slow, gentle compressor brings the loud and quiet moments a little closer, which makes the instruments feel like one recording. It ignores the deep bass when it decides how much to work, so the kick drum doesn’t make the whole song pump.
Warmth and width
A touch of saturation adds harmonics that make a mix feel fuller on small speakers. The stereo stage gets slightly wider above the bass, while everything below about 110 Hz stays in the middle. If your song already has a very wide or out-of-phase stereo image, widening is reduced or skipped so nothing disappears on a mono speaker.
Loudness and peaks
Last, a true-peak limiter raises the song to the loudness you chose. It looks ahead a few milliseconds and also checks the peaks between samples, which is where most clipping happens after a song is converted to MP3 or AAC. If reaching the target would take so much limiting that it starts to sound squashed, the tool stops short and tells you.
Loudness for each platform
Most streaming services turn every song up or down to the same loudness, measured in LUFS. A louder master doesn’t play louder there. It only loses punch.
| Where it’s going | Plays at | Pick |
|---|---|---|
| YouTube | about −14 LUFS | Streaming |
| Spotify | −14 LUFS (Loud setting −11, Quiet −19) | Streaming |
| Apple Music | −16 LUFS | Streaming |
| Deezer | −15 LUFS | Streaming |
| DJ sets, clubs, video edits | no normalization | Loud or Max |
Spotify recommends keeping true peak below −1 dBTP, and below −2 dBTP for masters louder than −14 LUFS. The Auto peak ceiling follows that.
Questions
Is my song uploaded anywhere?
No. All the processing runs in your browser on your own device. Nothing is sent to a server, so it also works with unreleased music.
Is this AI mastering?
It’s automatic mastering. The tool measures your song and sets the EQ, compression, width and loudness for it, using classic studio processing rather than a trained AI model. For most demos, beats and online releases the result is close to paid one-click services. For a release that really matters, a human mastering engineer is still the best choice.
Why does the original sound louder or quieter than the master?
With Same volume on, both versions play at the same loudness, so you hear the difference in tone and punch. Turn it off to hear the real level change.
Which loudness should I choose?
For YouTube, Spotify, Apple Music and most other streaming, choose Streaming. The services even out volume anyway, and a −14 LUFS master keeps more punch. Choose Loud or Max when the song will be played next to other loud tracks without normalization, for example in a DJ set or a video edit.
Can I master AI-generated music, for example from Suno?
Yes. Many AI tracks are already loud, so Streaming often turns them down a little while still improving tone and width. Whether you can release or monetize the song depends on the terms of the service that made it, not on mastering.
What is true peak?
Digital audio is stored as samples, but the actual waveform can rise above them between two samples. Those hidden peaks can clip when the song is converted to MP3 or AAC. The tool measures them by looking at four times as many points as the file has, and keeps them under the ceiling.
Will mastering fix a bad mix?
It can improve the overall tone, glue and loudness, but it works on the whole song at once. If the vocal is too quiet or one instrument is harsh, fix that in the mix first, then master.
Which file should I download?
WAV 24-bit keeps the full quality and is the best choice for distributors and video editors. WAV 16-bit is CD quality. MP3 is smaller and easy to share or send.
Is there a length limit?
Nothing is uploaded, so there’s no upload limit. The song is kept in memory while you work, so very long files (over about 15 minutes) can be slow or run out of memory, especially on phones.
Which browsers work?
Current versions of Chrome, Edge, Firefox and Safari, on a computer or a phone. A computer is faster for long songs.