Create a spectrogram

A waveform only shows HOW LOUD a recording is at each moment - a spectrogram additionally shows WHICH FREQUENCIES are present, and how they change over time. That makes it the tool of choice for audio engineers troubleshooting (a 50 Hz mains hum, high-frequency noise, a frequency range cut off by a poor microphone), for bioacoustics (bird calls, bat ultrasound) or simply for teaching, to make sound visible.

Technically, a short-time Fourier transform (STFT) breaks the signal into overlapping time windows and computes the frequency spectrum for each. The results are placed side by side, column by column: the x-axis is time, the y-axis is frequency (high at the top, low at the bottom), and colour intensity shows how loud that frequency is at that moment - the same teal brand colour as the waveform image, just two-dimensional now instead of a simple bar.

The computation runs entirely locally in the browser via a small, self-contained Fourier transform - no server, no upload, no third-party library.

Specifications

In 3 steps

1. Drop your audio file.
2. Choose image size and style (light or dark).
3. Download the spectrogram as a PNG.

Limitations: Shows linear frequency resolution (no logarithmic mel or Bark scale like professional analysis tools). There is no transparent variant like the waveform image, because colour itself carries the information here. Honest per-device length cap applies as for every audio tool.

FAQ

Related tools

Find the BPM · Find the key · Create a waveform image · Reverse audio