Spectrogram Viewer
See the frequencies in an audio file or your microphone over time.
See The Sound: Frequency Over Time
A spectrogram shows which frequencies are present at each moment — time runs left to right, pitch from bottom to top, and brightness is loudness. Drop in any audio or video file, or start the microphone for a live, scrolling view.
It reveals what a waveform hides: mains hum at 50 or 60 Hz, the sharp cut-off around 16 kHz that betrays an MP3 passed off as lossless, bird calls, harmonics, clipping, and even images hidden in audio. Choose a logarithmic or linear scale, the FFT window size and a colour map, and export the result as a PNG.
Key features
- Files and live microphone input.
- Log or linear frequency scale with labelled axes.
- FFT sizes from 1024 to 8192 for time or pitch detail.
- Colour maps — magma, viridis, heat and greyscale.
- Playhead and PNG export.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: Spectrogram Viewer
- Load audio
MP3, WAV, FLAC, OGG, M4A — or a video file. - Pick the scale
Logarithmic suits music and speech; linear shows high frequencies. - Adjust the window and range
Bigger windows sharpen pitch, smaller ones timing. - Play and export
Follow the playhead, then save the image.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Audio |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
How can I tell if a FLAC file is really lossless?
Look at the top of the spectrogram with the linear scale. A genuine CD-quality file usually has content up to around 20–22 kHz; a file transcoded from MP3 shows a hard, flat cut-off around 16–19 kHz.
What does FFT size change?
It is the trade-off between frequency and time resolution. A 8192-point window separates close pitches but smears quick events; a 1024-point window shows sharp timing but blurs pitch.
Why use a logarithmic scale?
Hearing is logarithmic: each octave doubles the frequency. On a log scale, music and speech spread across the whole height instead of being squeezed into the bottom few pixels.
Can I find hidden images in audio?
Yes — some musicians and puzzle makers draw pictures into the high frequencies of a track. They appear in a spectrogram with a linear scale and a wide dynamic range.
Is my audio uploaded?
No. Decoding and the FFT run in your browser, and the microphone view is never recorded.