Audio Spectrogram Generator
A windowed FFT of your own audio, drawn as a colour-mapped spectrogram with frequency and time rulers. Decoding happens on this device.
0 columns drawn · 512 frequency bins
Controls
About this tool
The decoder turns your audio into raw samples, a Hann (or Hamming/Blackman) window is applied per frame and a hand-written iterative radix-2 FFT produces the magnitude spectrum, which is converted to dB against your floor and ceiling and colour-mapped. Audio is decoded with the Web Audio API in this browser; nothing is uploaded, and the AudioContext and microphone stream are released when you leave the page. Frames are thinned to 1200 columns so long recordings still render quickly.
- 100% free — no account needed
- Runs in your browser
- Nothing is uploaded
Frequently asked questions
Is Spectrogram Generator really free?
Yes. Spectrogram Generator is completely free on PureBrowser — every feature, with no account, no trial, and no credit card.
Does Spectrogram Generator upload my data?
No. Spectrogram Generator runs entirely inside your browser, so anything you type, paste, or open stays on your own device.
Do I need to sign up or install anything?
Neither. There is no account and nothing to download — open the page and Spectrogram Generator is ready to use on desktop or mobile.
Does Spectrogram Generator work offline?
Once the page has loaded, yes. All of the processing happens locally in your browser, so it keeps working without a connection.
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