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FreeEQ8 is a professional-grade EQ8 / EQ Eight inspired parametric equalizer, free and open-source 8-band parametric EQ plugin for macOS, Linux, and Windows. Linear phase, dynamic EQ, match EQ, per-band drive, band linking, M/S processing, oversampling, and a real-time spectrum analyzer — all in a single, zero-cost plugin. Built with JUCE for VST3 and AU.
ProEQ8 is one of the most advanced EQs available, competing directly with top tools like ZL EQ and TDR Nova.
FabFilter Pro-Q alternative for $0–$20
5min Demo ProEQ8 is included!
| Feature | FreeEQ8 | FabFilter Pro-Q 4 | ZL Equalizer 2 | TDR Nova |
|---|---|---|---|---|
| Price | Free | $199 | Free | Free |
| Open Source | GPL-3.0 | — | AGPL-3.0 | — |
| Bands | 8 | 24 | 24 | 4 + HP/LP |
| Dynamic EQ | ✓ (thresh / ratio / atk / rel) | ✓ | ✓ | ✓ |
| Linear Phase | ✓ | ✓ | ✓ | — |
| Match EQ | ✓ | ✓ | ✓ (WIP) | — |
| Mid/Side | ✓ (per-band) | ✓ | ✓ | — (free) |
| Per-Band Drive | ✓ (tanh saturation) | — | — | — |
| Band Linking | ✓ (groups A/B) | — | — | — |
| Oversampling | ✓ (1×–8×) | internal | — | — |
| Adaptive Q | ✓ | — | — | — |
| Spectrum Analyzer | ✓ (4096-pt FFT) | ✓ | ✓ | ✓ |
| Level Meter | ✓ (peak + RMS) | — | — | — |
| Undo / Redo | ✓ | ✓ | ✓ | — |
| Collision Detection | ✓ (Pro) | ✓ | ✓ | — |
| Surround / Atmos | — | ✓ | — | — |
| Formats | VST3, AU | VST3, AU, AAX, CLAP | VST3, AU, LV2 | VST3, AU, AAX |
FreeEQ8 is the only free EQ that combines linear phase + dynamic EQ + match EQ + per-band saturation + band linking in one plugin.
Love FreeEQ8? ProEQ8 takes everything further.
ProEQ8 is the commercial big brother of FreeEQ8 — same rock-solid DSP engine, massively expanded. Included in the v2.1.0 release download.
| FreeEQ8 (Free) | ProEQ8 ($20) | |
|---|---|---|
| Bands | 8 | 24 |
| Saturation Modes | tanh | Tube · Tape · Transistor · Tanh |
| A/B Comparison | — | ✓ (instant snapshot toggle) |
| Auto-Gain Bypass | — | ✓ (RMS-matched) |
| Piano Roll Overlay | — | ✓ (note frequency reference) |
| Collision Detection | — | ✓ (overlapping band warnings) |
| Factory Presets | 30 | 30+ (genre-specific) |
| Dynamic EQ | ✓ | ✓ |
| Linear Phase | ✓ | ✓ |
| Match EQ | ✓ | ✓ |
| Mid/Side | ✓ | ✓ |
| Oversampling | ✓ | ✓ |
| Band Linking | ✓ | ✓ |
| Formats | VST3, AU | VST3, AU |
ProEQ8 is included in the macOS DMG download. A license key is required to unlock it — purchase through the link above to receive your key via email. Without a license, ProEQ8 runs in demo mode (mutes for 30 seconds every 5 minutes).
- 8 Independent Bands — full parametric control (frequency, Q, gain)
- 6 Filter Types per band: Bell, Low Shelf, High Shelf, High Pass, Low Pass, Bandpass
- Multiple Slopes — 12 / 24 / 48 dB/oct via cascaded biquad stages
- Per-Band Enable/Disable & Solo for A/B comparison and audition
- Parameter Smoothing (20ms linear interpolation, coefficients refreshed every 16 samples)
- Linear Phase Mode — symmetric FIR from combined biquad magnitude, overlap-add FFT convolution (2048-sample latency when active)
- Dynamic EQ — per-band envelope follower with sidechain bandpass, threshold, ratio, attack & release
- Per-Band Saturation / Drive — gain-compensated tanh waveshaper (0–100%)
- Mid/Side Processing — M/S encode/decode with per-band channel routing (Both / L-Mid / R-Side)
- Oversampling — 1x / 2x / 4x / 8x using JUCE polyphase IIR half-band filters
- Band Linking — link groups A/B propagate frequency (ratio), gain & Q (delta) changes
- Match EQ — capture a reference spectrum, analyze current signal, compute & apply per-bin correction via FFT
- Adaptive Q — automatically widens Q with increasing gain
- Real-Time Spectrum Analyzer — 4096-point FFT, Hann window, pre/post EQ toggle
- Interactive Response Curve — composite + per-band colored curves with dB/frequency grid
- Draggable Band Nodes — click-drag for freq/gain, shift+drag for Q, right-click context menu
- Stereo Level Meter — peak hold + RMS display
- Selected-Band Paradigm — 8 colored band buttons, single set of controls rebound per selection
- Dark Theme — resizable UI (750×550 to 1400×900)
- Output Gain (-24 dB to +24 dB)
- Scale (0.1x to 2x) — scales all band gains simultaneously
- Preset System — save / load / delete, 30 factory presets
- Undo / Redo — integrated with JUCE UndoManager via APVTS
- State Save/Restore — all settings persist in your DAW project
- Stereo processing (or Mid/Side)
- Sample rates: 44.1 kHz to 192 kHz+
- Transposed Direct Form II biquad with double-precision (64-bit) internal arithmetic
- RBJ Audio EQ Cookbook coefficients
- Zero latency in minimum-phase mode; linear phase adds 2048 samples
- Low CPU usage (disable unused bands, lower oversampling to reduce load)
- macOS: 10.13 High Sierra and later (universal binary: Intel + Apple Silicon)
- Linux: Debian/Ubuntu 20.04+ (VST3 only; see build instructions for dependencies)
- Windows: 10 and later (64-bit)
- DAWs tested: Ableton Live 10+, Logic Pro, FL Studio, Bitwig, REAPER
- Formats: VST3, AU (macOS), Standalone (all platforms)
git clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8
./build_macos.shgit clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8
./build_linux.sh # installs deps via apt, then buildsgit clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8
.\build_windows.ps1Plugins will be automatically installed to your system plugin directories.
- Xcode Command Line Tools:
xcode-select --install - CMake 3.15+:
brew install cmake
- GCC 9+ or Clang 10+
- CMake 3.15+
- JUCE system dependencies (installed automatically by
build_linux.sh):libasound2-dev libjack-jackd2-dev libfreetype6-dev libx11-dev libxcomposite-dev libxcursor-dev libxext-dev libxfixes-dev libxinerama-dev libxrandr-dev libxrender-dev libwebkit2gtk-4.0-dev
- Visual Studio 2019+ with C++ build tools
- CMake 3.15+
git clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8If you already cloned without --recursive:
git submodule update --init --recursive
cd JUCE && git checkout 7.0.12 && cd ..macOS:
chmod +x build_macos.sh
./build_macos.shLinux:
chmod +x build_linux.sh
./build_linux.shWindows:
.\build_windows.ps1macOS (automatic):
- VST3:
~/Library/Audio/Plug-Ins/VST3/FreeEQ8.vst3 - AU:
~/Library/Audio/Plug-Ins/Components/FreeEQ8.component
Linux (manual):
- Copy
build/FreeEQ8_artefacts/Release/VST3/FreeEQ8.vst3to~/.vst3/
Windows (manual):
- Copy
build\FreeEQ8_artefacts\Release\VST3\FreeEQ8.vst3to:C:\Program Files\Common Files\VST3\
- Ableton Live: Preferences → Plug-ins → Rescan
- Logic Pro: Automatic detection
- FL Studio: Options → Manage plugins → Find plugins
| Parameter | Range | Scale | Description |
|---|---|---|---|
| Frequency | 20 Hz – 20 kHz | Logarithmic | Center/cutoff frequency |
| Q | 0.1 – 24 | Logarithmic | Bandwidth (0.1 = wide, 24 = narrow) |
| Gain | -24 dB to +24 dB | Linear | Boost/cut amount |
| Slope | 12 / 24 / 48 dB/oct | Discrete | Filter steepness (1/2/4 cascaded stages) |
| Drive | 0 – 100 % | Linear | Per-band tanh saturation amount |
| Channel | Both / L-Mid / R-Side | Discrete | Per-band channel routing |
| Link Group | -- / A / B | Discrete | Band linking group |
| Dyn Threshold | -60 dB to 0 dB | Linear | Dynamic EQ threshold |
| Dyn Ratio | 1:1 – 20:1 | Logarithmic | Dynamic EQ compression ratio |
| Dyn Attack | 0.1 – 100 ms | Logarithmic | Dynamic EQ attack time |
| Dyn Release | 1 – 1000 ms | Logarithmic | Dynamic EQ release time |
| Output | -24 dB to +24 dB | Linear | Master output level |
| Scale | 0.1x – 2x | Linear | Global gain multiplier |
Band: Bell filter
Q: 6-12 (narrow)
Gain: -6 to -12 dB
Band: Bell/Shelf filter
Q: 0.5-2 (wide)
Gain: ±3 to ±6 dB
Band: HighPass filter
Freq: 20-120 Hz (depends on source)
Q: 0.7 (standard)
Kick Drum:
- Band 1: Bell @ 60Hz, Q=1.5, +4dB (sub thump)
- Band 2: Bell @ 200Hz, Q=3, -3dB (cardboard removal)
- Band 3: Bell @ 3kHz, Q=2, +2dB (beater click)
Acoustic Guitar:
- Band 1: HighPass @ 80Hz (rumble removal)
- Band 2: Bell @ 200Hz, Q=1.5, -2dB (boominess)
- Band 3: Bell @ 3kHz, Q=1, +3dB (presence)
- Band 4: HighShelf @ 8kHz, +2dB (air)
Vocals:
- Band 1: HighPass @ 80Hz (rumble)
- Band 2: Bell @ 250Hz, Q=2, -3dB (muddiness)
- Band 3: Bell @ 1kHz, Q=1, +2dB (body)
- Band 4: Bell @ 5kHz, Q=2, +3dB (clarity)
┌──────────────────────────────────────────────────────┐
│ FreeEQ8 Audio Processor │
├──────────────────────────────────────────────────────┤
│ Input Buffer (Stereo) │
│ ↓ │
│ Spectrum FIFO (pre-EQ) ──→ UI spectrum display │
│ ↓ │
│ ┌─── IF linear_phase ───┐ ┌── ELSE (min-phase) ──┐│
│ │ Build composite mag │ │ Oversampling ↑ (opt.) ││
│ │ response from biquads │ │ ↓ ││
│ │ ↓ │ │ M/S Encode (optional) ││
│ │ FIR convolution │ │ ↓ ││
│ │ (overlap-add FFT, │ │ Per-band loop ×8: ││
│ │ 4096-tap, 8192 FFT, │ │ ├ Dyn EQ envelope ││
│ │ 2048-sample latency) │ │ ├ Smooth + update ││
│ │ ↓ │ │ │ coefficients ││
│ │ Output Gain │ │ ├ Cascaded biquads ││
│ └───────────────────────┘ │ │ (1/2/4 stages) ││
│ │ └ Drive (tanh) ││
│ │ ↓ ││
│ │ Output Gain & Scale ││
│ │ ↓ ││
│ │ M/S Decode (optional) ││
│ │ ↓ ││
│ │ Oversampling ↓ (opt.) ││
│ └───────────────────────┘│
│ ↓ │
│ Match EQ correction (FFT overlap-add, optional) │
│ ↓ │
│ Spectrum FIFO (post-EQ) ──→ UI spectrum display │
│ ↓ │
│ Output Metering (peak hold + RMS) │
│ ↓ │
│ Output Buffer (Stereo) │
└──────────────────────────────────────────────────────┘
- Filter Structure: Transposed Direct Form II biquad (Biquad.h)
- Coefficient Calculation: RBJ Audio EQ Cookbook
- Smoothing: Linear interpolation over 20ms
- Update Rate: Coefficients refreshed every 16 samples during smoothing
- Precision: Double-precision (64-bit) coefficients and internal state; float I/O
- Linear Phase: 4096-tap symmetric FIR, 8192-point FFT, overlap-add convolution
- Dynamic EQ: One-pole envelope follower with sidechain bandpass at band frequency
- Spectrum: 4096-point FFT, Hann window, lock-free SPSC FIFO
FreeEQ8/
├── Source/
│ ├── PluginProcessor.h/.cpp # Main audio processor
│ ├── PluginEditor.h/.cpp # UI editor & layout
│ ├── DSP/
│ │ ├── Biquad.h # Biquad filter implementation
│ │ ├── EQBand.h # EQ band with smoothing, drive & dynamic EQ
│ │ ├── SpectrumFIFO.h # Lock-free FFT FIFO
│ │ ├── LinearPhaseEngine.h # FIR-based linear-phase EQ engine
│ │ └── MatchEQ.h # Reference capture & correction curve
│ ├── UI/
│ │ ├── ResponseCurveComponent.h/.cpp # EQ curve + spectrum + nodes
│ │ └── LevelMeter.h # Stereo peak/RMS level meter
│ ├── Presets/
│ │ └── PresetManager.h/.cpp # Preset save/load system
│ ├── UpdateChecker.h # GitHub releases update checker
│ └── LicenseValidator.h # Offline license key validation
├── server/
│ ├── stripe-webhook.js # Cloudflare Worker for Stripe → license
│ ├── wrangler.toml # Wrangler deployment config
│ └── package.json # Server dependencies (wrangler)
├── STRIPE_SETUP.md # ProEQ8 Stripe deployment guide
├── docs/ # Screenshots & assets
├── JUCE/ # JUCE framework (submodule)
├── build/ # Build output (ignored)
├── CMakeLists.txt # CMake config (FreeEQ8 + ProEQ8 targets)
├── build_macos.sh # macOS build script
├── build_linux.sh # Linux build script
├── build_windows.ps1 # Windows build script
├── package_macos.sh # macOS DMG packaging script
├── .gitignore # Git ignore rules
└── README.md # This file
- Real-time spectrum analyzer
- Interactive frequency response curve display
- Draggable band nodes on curve
- Adaptive Q implementation
- Band solo/audition mode
- Preset management system
- Multiple filter slopes (12/24/48 dB/oct) via cascaded biquads
- Mid/Side processing mode with M/S encode/decode
- Per-band channel routing (Both / L-Mid / R-Side)
- Oversampling options (1x, 2x, 4x, 8x)
- Output metering with peak hold and RMS
- Resizable UI (700×500 to 1400×900)
- Linear phase mode (FIR convolution via overlap-add FFT)
- Dynamic EQ capabilities (per-band envelope follower with threshold/ratio/attack/release)
- Band linking (link groups A/B with delta-based freq/gain/Q propagation)
- Per-band saturation/drive (gain-compensated tanh waveshaper)
- Undo/Redo system (integrated with APVTS UndoManager)
- Match EQ functionality (capture reference spectrum, compute & apply correction)
- Online license activation (2 devices per key) with Stripe checkout
- ProEQ8 commercial target (24 bands, 4 saturation modes, A/B, auto-gain)
- Cloudflare Worker license server + Resend email delivery
- Demo mode for unactivated ProEQ8 (mutes 30s every 5min)
- Standalone app included in all platform packages
- Hardened ProEQ8 license: device-bound activation, 7-day re-verify, 30-day offline grace
- Server /verify endpoint for periodic re-validation
- Obfuscated signing secret in binary
- Fixed JUCE 7.0.12 API compatibility
Contributions are welcome! Here's how you can help:
- Fork the repository
- Create a feature branch:
git checkout -b feature/amazing-feature - Commit your changes:
git commit -m 'Add amazing feature' - Push to the branch:
git push origin feature/amazing-feature - Open a Pull Request
- Follow existing code style
- Add comments for complex DSP algorithms
- Test on both macOS and Windows if possible
- Update documentation for new features
- 🎨 UI/UX improvements
- 🔊 Additional filter types
- 🐛 Bug fixes and optimizations
- 📚 Documentation improvements
- 🧪 Unit tests
- ✅ Standalone app now included in macOS DMG, Windows ZIP, Linux tar.gz
- ✅ Hardened ProEQ8 license system: device-bound activation (2 systems per key)
- ✅ Periodic server re-verification every 7 days (30-day offline grace period)
- ✅ XOR-obfuscated signing secret in binary
- ✅ Server
/verifyendpoint for client re-validation - ✅ Background license re-verify on ProEQ8 editor open when overdue
- ✅ Fixed
inPostBody→inPostDatafor JUCE 7.0.12 API - ✅ Added
workflow_dispatchtrigger for manual CI runs
- ✅ Online license activation for ProEQ8 (2-device limit per key)
- ✅ Stripe Checkout → Cloudflare Worker webhook → HMAC-signed license key → email via Resend
- ✅ Device fingerprinting (hardware UUID on macOS, MachineGuid on Windows, machine-id on Linux)
- ✅ Demo mode for unactivated ProEQ8 (mutes 30s every 5min)
- ✅ Deactivation support to free device slots
- ✅ ProEQ8 commercial target: 24-band parametric EQ (same source, PROEQ8=1 compile flag)
- ✅ 4 saturation modes per band (Pro): Tanh, Tube, Tape, Transistor
- ✅ A/B comparison (Pro): instant snapshot toggle with Copy A→B / B→A
- ✅ Auto-gain bypass: RMS-matched loudness compensation for honest A/B listening
- ✅ Piano roll overlay (Pro): musical note reference lines C1–C8 on the response curve
- ✅ Collision detection (Pro): amber warning when bands overlap within 1/3 octave
- ✅ Update checker: background thread checks GitHub releases, shows banner when new version available
- ✅ License validator + activation dialog (Pro): offline license keys, demo mode (mute 30s every 5min)
- ✅ Stripe webhook serverless function: Cloudflare Worker generates license keys, emails via Resend
- ✅ 30 genre-specific factory presets
- ✅ Fixed preset directory using product name (not hardcoded)
- ✅ Fixed factory preset OOB access for ProEQ8's 24-band layout
- ✅ Linear phase mode: symmetric FIR from combined biquad magnitude, overlap-add FFT convolution (2048-sample latency)
- ✅ Dynamic EQ: per-band envelope follower with sidechain bandpass, threshold, ratio, attack & release
- ✅ Band linking: link groups A/B propagate freq (ratio-based), gain & Q (delta-based) changes
- ✅ Per-band saturation/drive: gain-compensated tanh waveshaper (0–100%)
- ✅ Undo/Redo system via juce::UndoManager integrated with APVTS
- ✅ Match EQ: capture reference spectrum, compute per-bin correction, FFT-based application
- ✅ New parameters: drive, dynamic EQ (threshold/ratio/attack/release), link group per band
- ✅ Updated UI: undo/redo buttons, dynamic EQ toggle + threshold, link group selector, drive knob
- ✅ Multiple filter slopes: 12/24/48 dB/oct per band via cascaded biquad stages
- ✅ Mid/Side processing mode with stereo encode/decode
- ✅ Per-band channel routing: Both / Left(Mid) / Right(Side)
- ✅ Oversampling: 1x / 2x / 4x / 8x using JUCE polyphase IIR
- ✅ Output level metering with peak hold and RMS display
- ✅ Resizable UI with proportional layout (750×550 to 1400×900)
- ✅ New global controls: Oversampling selector, Processing Mode selector
- ✅ Per-band controls: Slope selector, Channel routing selector
- ✅ Real-time spectrum analyzer (4096-point FFT, pre/post EQ toggle)
- ✅ Interactive frequency response curve display with grid
- ✅ Draggable band nodes (click-drag for freq/gain, shift+drag for Q)
- ✅ Per-band colored curves with composite response overlay
- ✅ Adaptive Q DSP implementation (auto-scales Q with gain)
- ✅ Band solo/audition mode ("S" button per band)
- ✅ Preset management (save/load/delete, 8 factory presets)
- ✅ Complete UI overhaul (900×620, dark theme, response curve on top)
- ✅ Right-click context menu on band nodes (type change, enable/disable)
- ✅ Attribution updated to Gary Doman (GareBear99)
- ✅ Added output gain control (-24dB to +24dB)
- ✅ Added global scale parameter (0.1x to 2x)
- ✅ Added adaptive Q toggle (UI only, DSP pending)
- ✅ Enhanced UI layout with global controls
- ✅ Fixed JUCE 7.0.12 compatibility issues
- ✅ Fixed VST3 build on macOS with Xcode 12
- ✅ Improved parameter smoothing
- ✅ Updated build scripts for reliability
- 8-band parametric EQ
- RBJ biquad filters (Bell, Shelf, HP, LP)
- Parameter smoothing (20ms)
- State save/restore via APVTS
- CMake build system for VST3/AU
- Initial prototype
This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.
Note: JUCE has its own licensing requirements. For commercial use, you may need a JUCE license. See JUCE Licensing for details.
FreeEQ8 is an original implementation of a parametric EQ plugin. It is:
- NOT affiliated with, endorsed by, or derived from Ableton AG
- NOT a clone of Ableton's EQ Eight
- An independent, open-source project
- Built using public-domain DSP algorithms (RBJ Audio EQ Cookbook)
- Changing oversampling mid-playback may cause a brief click
- Linear phase mode adds 2048 samples of latency (reported to DAW via
setLatencySamples) - Match EQ capture is mono-summed; correction is per-channel
- Linear phase mode does not currently apply M/S, per-band drive, or dynamic EQ (minimum-phase path only)
Report issues at: https://github.com/GareBear99/FreeEQ8/issues
- Disable unused bands to reduce CPU load
- Use wider Q values (lower numbers) for smoother processing
- Enable adaptive Q for automatic gain-dependent Q adjustment
- Start with subtractive EQ (cut problem frequencies)
- Use narrow Q to identify resonances
- Use wide Q for musical boosts
- Check your EQ in mono to avoid phase issues
- Stack multiple bell filters at the same frequency with different Q values
- Automate the scale parameter for dramatic filter sweeps
- Use extreme Q values (>10) for creative resonances
- JUCE Framework - Cross-platform audio plugin framework
- Robert Bristow-Johnson - RBJ Audio EQ Cookbook
- Audio Plugin Development Community - For knowledge sharing
- Ableton - For inspiration (not affiliation)
FreeEQ8 is free and open source. If it's useful to you, consider supporting development:
Other ways to help:
- ⭐ Star this repo — helps others find FreeEQ8
- 🐛 Report bugs — open an issue
- 🔀 Contribute — PRs are welcome
- 📣 Spread the word — tell a producer friend
- Issues: GitHub Issues
- Discussions: GitHub Discussions
- Email: neovectr.inc@gmail.com
Other Projects by Me!
https://github.com/GareBear99/TizWildinEntertainmentHUB
https://github.com/GareBear99/awesome-audio-plugins-dev
https://github.com/GareBear99/PaintMask_Free-JUCE-Plugin
https://github.com/GareBear99/WURP_Toxic-Motion-Engine_JUCE
https://github.com/GareBear99/RiftWaveSuite_RiftSynth_WaveForm_Lite
https://github.com/GareBear99/AETHER_Choir-Atmosphere-Designer
https://github.com/GareBear99/WhisperGate_Free-JUCE-Plugin
https://github.com/GareBear99/Therum_JUCE-Plugin
https://github.com/GareBear99/MixMaid
https://github.com/GareBear99/BassMaid
https://github.com/GareBear99/SpaceMaid
https://github.com/GareBear99/GlueMaid
https://github.com/GareBear99/XyloCore
Built with ❤️ by Gary Doman (GareBear99/TizWildin)
"Great sound shouldn't cost anything"


