Audio Spectrogram Generator
Turn audio into a spectrogram image showing how its frequencies change over time.
Fill in the form and press “Generate spectrogram” to see the result here.
How to use it
- 1Choose a file, or drag it onto the upload area.
- 2Press the button. Your browser decodes the file locally.
- 3Read the results. Nothing was uploaded, so there is nothing to clean up.
About the Audio Spectrogram Generator
Time runs left to right, frequency bottom to top on a logarithmic scale, and brightness shows how much energy is present at each point.
The classic use is spotting a transcode: a hard horizontal cut-off near the top means the audio was once a low-bitrate file, no matter what format it is in now. A genuine lossless recording has content running all the way up.
The analysis window is a trade-off that cannot be avoided - a longer window resolves frequency better and time worse. This runs a windowed FFT on your own device with no library and no upload.
Questions people ask
Is my file uploaded?
No. The file is decoded by your own browser and the result is displayed locally. Nothing leaves your device, there is nothing on a server to delete, and this works with no network connection at all.
Why does a large file fail?
Decoding holds the audio in memory uncompressed - roughly 10 MB for every minute of stereo. Long recordings run out of memory in a browser tab, which is why there is a size limit. The queued FFmpeg tools handle bigger files.
Is it free, and do I need an account?
Yes, it is free, and there is no account, no sign-up and no watermark on the result. The project is funded by optional donations.