Version 1.2.3 — available now

gFractor

A powerful and flexible spectrum
analyzer for modern audio production.

Free Download Explore features Beta Try 1.3.3
Read the full manual

Spectrum, scope, goniometer, loudness, and the full picture, in one window.

VST3 · AU · Standalone · macOS, Windows, Linux · Free, no account

Introduction

See it in action

What makes it different

Tools that think like musicians

From sound design to mixing and mastering — gFractor gives you precise visual feedback and deep insight into your audio at every stage of the workflow.

01 — Advanced Analysis Modes

Three modes.
Every perspective.

Switch between Mid/Side, Left/Right, and Transient/Tone analysis to explore your signal from any angle. Monitor individual components — isolate transients from tonal content, or hear the mid and side channels in complete separation.

Mid / Side Left / Right Transient / Tone Component monitoring
gFractor spectrum analyzer with Mid/Side channel mode controls
02 — Signal Comparison

Main and sidechain,
side by side

Visually compare your main signal against a sidechain reference — instantly revealing spectral relationships between tracks. Swap main and sidechain with a single key press for rapid A/B analysis without breaking your flow.

Main signal Sidechain One-key swap Visual overlay
gFractor overlaid primary and secondary spectrum curves
03 — Stereo Analysis

Your stereo field,
fully mapped.

Comprehensive stereo visualization in one place: a goniometer for phase and imaging, a correlation meter for mono compatibility, and correlation broken down per octave — so a phase problem in the sub can't hide behind an in-phase midrange.

Goniometer Correlation meter Correlation per octave Band-pass filter
gFractor stereo analysis with goniometer, correlation and width per octave
04 — Target Save & Compare

Save a target.
Match it later.

Capture any Peak Hold curve as a reusable target and save it to a file. Load it back in any session to compare against your current track — perfect for matching tonal balance across mixes or checking a master against a reference.

Peak Hold capture Save / Load Reference overlay Cross-session
gFractor save, load and target curve controls
05 — Loudness Metering

Loudness,
to spec.

A full ITU-R BS.1770-4 / EBU R128 loudness meter sits alongside the analyzer. Track short-term and integrated LUFS, loudness range, and dynamics at a glance — with momentary, short-term, and peak maximums held since the last reset. Switch to LU to read against your delivery target, and check crest factor alongside PSR and PLR.

Short-term & Integrated Loudness Range Dynamics LU vs target
gFractor LUFS loudness metering panel

Available now

Free. No compromises.

No demo mode. No watermark. No 30-day trial.
Professional-grade tools should be in everyone's hands.

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Vote for gFractor as Favorite Utility in the KVR Audio Readers’ Choice Awards 2026. It’s free and helps others discover gFractor.

v1.2.3 Previous versions
~/gFractor — CHANGELOG.md
$ cat v1.2.3.md
# gFractor 1.2.3
Released 2026-09-24
## New
+ LUFS / LU pills switch the loudness readouts between absolute LUFS and LU relative to a target
+ Draggable TARGET badge sets the target in 0.5 LU steps; the bar marks it as a dashed line at 0 LU
+ CREST readout: the plain peak-to-RMS ratio in dB, over the same 3 s window as the peak
+ Reset On Play restarts the loudness measurement whenever the host transport rolls (off by default)
+ The per-octave stereo chart now plots correlation per band, on an 8192-point FFT so 31.5 Hz resolves
+ Scope dB cursor: a horizontal line follows the pointer, labelled in dB relative to the lane's zero line
+ The sidechain draws in the scope as a ghost envelope beneath the main curves, so G works there too
+ Export any view as a branded 2x PNG with E or the camera pill in the header
## Changed
* New Meters preferences tab between Display and System — target level, LUFS Min / Max, Reset On Play
* Preference tabs are sized to their captions, and the panel is widened to 620 px so they fit on Windows
* An empty octave band reads zero correlation instead of painting a confident bar off noise
## Fixes
- A target curve saved at one FFT size and reloaded at a smaller one read past the end of its data
- The GHOST pill state survives a reopened editor; reference mode is dropped when the window closes
- Switching channel mode restarts the ghost trace's Transient/Tonal envelopes
Beta

Preview channel

Try the next release early.

New features, fresh fixes — and the occasional rough edge. Feedback helps shape the next stable build.

v1.3.3 beta Previous versions
~/gFractor — CHANGELOG.md
$ cat v1.3.3-beta.md
# gFractor 1.3.3 beta
Released 2026-10-14
## New
+ Reference file: A/B against a WAV, AIFF, FLAC or Ogg file (plus MP3 / M4A on macOS) instead of a sidechain
+ Reference strip: waveform overview, draggable loop region, transport, recent files, MATCH loudness and trim
+ REF and GHOST in the waterfall: the ghost splits the spectrogram, live above and reference below
+ Goniometer: a polar display alongside Lissajous (Settings > Meters > Display)
+ Spectrum: To Nyquist toggle, 32768 / 65536 FFT sizes, 32x / 64x overlap, and Min Hz down to 1 Hz
+ Oscilloscope time offset: Alt+click sets the left edge, Alt+drag slides the phase, Alt+double-click resets
+ LUFS meter: a DC OFFSET readout, green below -60 dBFS, amber to -40 and red above
+ Settings > Display: Text Size (100 / 115 / 130%) for legibility at small UI scales
## Changed
* GHOST is split like MID / SIDE: its speaker listens to the reference, its label shows the ghost trace
* Listening to the reference crossfades over ~10 ms instead of cutting, and no longer changes the main curves
* Inside a host, shortcuts apply only after a click in the plug-in; Cmd/Ctrl/Alt chords go to the DAW
* LUFS meter: default LU target is -7 LUFS (was -23); a target you already set is kept
* The bundled JetBrains Mono font now loads in all three weights
* Spectrum FFT is 16-20 % faster per block; no GPU readback stalls in the goniometer on Windows
* macOS 11.0 is now the minimum (was 10.13)
* Removed: the target-curve overlay and its SAVE / LOAD / TARGET pills (T is unbound)
## Fixes
- HOLD is saved with the session and presets instead of switching off when the window reopens
- Bound keys (R, S, Z, Tab, ...) reach the DAW again; a captured key in Settings > Keys no longer stays armed
- Lowering the FFT size no longer lifts the spectrum's low end up to the bin width
- Goniometer edge labels named the opposite channel; host loops off a division no longer blank the scope
- Sessions restore the reference strip, PLAY and MATCH reliably; a sample-rate change re-decodes the loop
- LUFS readouts stay inside a short panel, and cached text is sharp at fractional UI scales
- Windows: a fix for the sluggish UI / high CPU use reported on 1.3.2. Still seeing it? Tell us which host and Windows version

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