// free · browser-based · no signup
Free Online Audio Tools
Spectrogram · EQ · Compressor · Limiter
Two tools that run entirely in your browser. See your sound as a live 3D & 2D spectrogram, then shape it with an 8-band EQ, compressor and limiter — and export the result. Nothing uploaded, nothing installed.
The tools
Spectral Field
A live 3D & 2D spectrogram / FFT analyzer. Frequency, level and time build into a surface you can orbit — with pitch/note readout, mic input, whole-track mode, and A/B comparison.
Open tool EQ · comp · limitSignal Dashboard
A free online EQ, compressor and limiter. An 8-band parametric EQ you drag by hand, a full dynamics compressor and a brickwall limiter — with 33 presets, live metering, and WAV, FLAC or 320 kbps MP3 export.
Open tool 10× oscillatorTone Forge
A free online 10× oscillator synth. Ten waves in root C — sine, triangle, saw, square or drawn by hand — each with its own start time, length, attack, gain, pan and effects, through a master EQ, compressor and limiter.
Open toolSee it, then shape it
Most audio problems are invisible until you look at them. A muddy mix, a resonant room, a harsh vocal, a rumble you can feel but not hear — they all show up instantly on a spectrogram, and they all get fixed with an EQ, a compressor and a limiter. songtools.music gives you both halves of that job, free, with nothing to install and nothing uploaded.
Everything here runs locally using the Web Audio API and WebGL2. Your files never leave your device — they are read straight from disk, processed on your own machine, and, when you export, written back to your downloads folder without ever touching a server.
1 · See it — the online spectrogram
A spectrogram is a visual map of sound. Instead of the single squiggly line of a sound wave (a waveform), it splits audio into its individual frequencies using a Fast Fourier Transform (FFT) and shows three things at once: which frequencies are present, how loud each one is (in decibels), and when they happen over time. Bright, tall regions are strong tones; faint regions are quiet or empty. (It's also commonly misspelled "spectogram.")
Most spectrogram tools give you a flat 2D spectrogram — frequency up the side, time across the bottom, loudness as color. Spectral Field shows that same information, then lifts loudness into a third dimension so you get a full 3D spectrogram you can rotate, zoom and read from any angle. Look at it straight down and it reads like a classic 2D spectrogram; tilt it and the peaks of your sound waves rise into a landscape.
It works two ways. Load a track and analyze the whole file as one static shape, or switch to the live spectrogram and watch it scroll in real time as audio plays or straight from your microphone — a true live, real-time view of whatever you're recording or listening to.
Real-time FFT
Live spectrogram that scrolls as it plays, or a static whole-track shape you can orbit.
True 3D surface
Frequency × time × loudness on a GPU-rendered mesh — rotate, zoom, pan and probe any point.
Note & pitch detection
Reads out peak frequency and the nearest musical note with cents offset.
A/B comparison
Overlay two tracks or view their difference to see how their tonal balance really differs.
2 · Shape it — the online EQ, compressor & limiter
Once you can see the problem, Signal Dashboard fixes it. An 8-band parametric EQ — a high-pass filter, a low shelf, four fully sweepable peaking bands, a high shelf and a low-pass filter — lets you cut the 300 Hz mud, lift the 3 kHz presence or filter rumble below 40 Hz. You drag the bands directly on the response curve, which sits on top of a live spectrum of your audio, so you are aiming at something real rather than guessing.
After the EQ comes a full dynamics compressor with threshold, ratio, knee, attack, release and makeup gain, and then a brickwall limiter with an output ceiling. The compressor evens out the gap between the loudest and quietest moments; the limiter makes sure nothing ever crosses your ceiling. Gain-reduction meters show you exactly how hard each stage is working.
33 presets cover the usual starting points — vocals and podcasts, acoustic and electric guitar, bass, kick, snare, drum bus, piano and synth, plus full mastering chains for streaming, club, hip-hop and rock, and character curves like warm analog, telephone and vinyl. Tap Bypass at any time to hear the raw signal, keep two full settings snapshots in the A/B slots, and export the finished result as a 24-bit WAV, a lossless FLAC or a 320 kbps MP3.
Draggable 8-band EQ
Move any band on the curve, scroll to change its Q, double-click to switch it off.
Compressor + limiter
Full dynamics control with live gain-reduction metering on both stages.
33 presets
Vocal, instrument, master and character chains — each one a labelled starting point.
WAV, FLAC or MP3
Renders your file through the exact chain you're hearing, on your own machine — 24-bit, lossless or 320 kbps.
The two together
They're built to be used as a loop. Find the problem in the spectrogram — a resonant peak, a rumble under 40 Hz, harshness sitting around 3 kHz. Fix it in the EQ, compressor and limiter, listening on Bypass to check you've actually improved things. Verify by exporting a lossless file and dropping it back into the spectrogram, or by loading the before and after as A and B to see the difference laid out side by side.
Seeing, fixing and confirming are three separate jobs, and doing them with your ears alone is how mixes go wrong. Both tools are free, both are private, and neither one asks you to sign up.
How to use them
Making a spectrogram online
- Open the tool. Launch Spectral Field — it loads instantly, no signup.
- Feed it sound. Drag an audio file onto the page, click Open file, hit Mic for live input, or press Demo to try it.
- Read the surface. Watch frequencies rise as peaks; hover any point to read its exact frequency, dB and time, plus the nearest note.
- Dial it in. Adjust FFT size, smoothing, the dB window and the color palette, or switch between log and linear frequency.
- Compare. Load a second track to A/B their spectra and spot differences in bass, mids and highs.
EQ'ing, compressing and limiting a track
- Open the tool. Launch Signal Dashboard and drop in a file, or run the demo loop.
- Start from a preset. Pick the one matching your source — Vocal — clarity, Drum bus glue, Master — glue — and read the note under the menu explaining what it does.
- Shape the EQ. Drag the numbered dots on the curve: left and right for frequency, up and down for gain, scroll for Q. The live spectrum behind the curve shows you what you're aiming at.
- Set the dynamics. Lower the compressor threshold until the GR meter shows a few dB on peaks, then set the limiter ceiling — −1 dB is a safe target for streaming.
- Check and export. Hit Bypass to compare against the raw signal, then Export for a 24-bit WAV, a lossless FLAC or a 320 kbps MP3 of exactly what you're hearing.
Why browser-based
100% private
No upload, no account, no watermark. Your audio is read and processed on your own device.
Nothing to install
No plugin format to match, no DAW, no license key. Open a tab and it works.
Mic, file or demo
Drag in WAV, MP3, FLAC, OGG or M4A, use your microphone live, or run the built-in demo.
Free, with no limits
No trial length, no export cap, no locked features. Both tools, all of it, free.
Frequently asked questions
What is an online spectrogram?
An online spectrogram is a browser tool that turns sound into a picture of frequency over time. It runs a Fast Fourier Transform (FFT) on your audio and plots which frequencies are present, how loud they are, and when — so you can literally see notes, harmonics, noise and silence.
What does the online EQ, compressor and limiter do?
Signal Dashboard changes how your audio sounds. The 8-band parametric EQ raises or lowers specific frequency ranges — cutting muddiness, adding presence, filtering rumble. The compressor evens out the difference between loud and quiet moments. The limiter puts a hard ceiling on the peaks so nothing clips. You can hear every change in real time and export the processed audio as a 24-bit WAV.
Are these tools free?
Yes. Both the spectrogram and the EQ, compressor and limiter are completely free, with no signup, no watermark and no limits. Everything runs locally in your browser.
Do my audio files get uploaded to a server?
No. All analysis and processing happens on your own device using the Web Audio API and WebGL2. Your audio never leaves your computer, so it stays private and works even offline once the page is loaded. Exported WAV files are rendered on your machine too.
What audio formats can I use?
Both tools open common audio files — WAV, MP3, FLAC, OGG, M4A and more — take live input from your microphone, and include a built-in demo signal. Signal Dashboard exports 24-bit WAV, lossless FLAC or 320 kbps MP3.
What's the difference between a compressor and a limiter?
They're the same kind of processor at different intensities. A compressor turns down anything above its threshold by a ratio — 3:1 means 3 dB over the threshold becomes 1 dB over — which smooths out the performance. A limiter is a compressor with a very high ratio and a very fast attack, used as a safety net: it stops peaks from ever crossing a ceiling. In practice you compress for feel and limit for protection.
Which preset should I start with?
Pick the one that matches your source — there are 33, grouped into Utility, Vocal, Instrument, Master and Character. Vocal — clarity suits most spoken and sung takes, Master — glue is the gentlest option for a finished mix, and Flat gives you an untouched starting point. Every preset is a starting point, not a destination: load one, then drag the curve and watch the meters.
Do the two tools work together?
Yes — that's the intended workflow. Use the spectrogram to find the problem, then open the EQ, compressor and limiter to fix it, export the file, and drop it back into the spectrogram to confirm the change. Seeing it, fixing it and verifying it are three separate jobs.
What makes this different from a normal 2D spectrogram?
A flat 2D spectrogram shows frequency, time and loudness-as-color on a plane. Spectral Field renders that same data as an interactive 3D surface — frequency on one axis, time on another, and loudness as height — which you can rotate, zoom and probe. Viewed top-down it reads like a 2D spectrogram; tilted, it becomes a 3D landscape. It also reports peak frequency, nearest musical note, RMS level and spectral centroid, and can compare two tracks A/B.
Can I get a live spectrogram from my microphone?
Yes. Click Mic and Spectral Field shows a live, real-time spectrogram of whatever your microphone hears — great for tuning instruments, checking a room, analyzing a voice, or watching sound waves as they happen. Mic input is analyzed on your device and is never recorded or uploaded.
Can I export the processed audio?
Yes — as a 24-bit WAV, a lossless FLAC, or a 320 kbps MP3. Signal Dashboard renders your file through the exact EQ, compressor and limiter settings you're hearing, and every export is tagged with songtools.music plus a full record of the chain you used. The render happens offline on your own device, so nothing is uploaded and there's no quality loss from a round trip through a server.
Do these work on mobile?
Both run in modern mobile browsers — the spectrogram needs WebGL2 and the EQ needs the Web Audio API, and current iOS and Android browsers support them. A desktop with a mouse or trackpad still gives you the most control for orbiting the 3D surface and dragging EQ bands precisely.