Our free granular synthesizer chops any audio file into microscopic grains (5–100ms) and recombines them with pitch-shifting, reverb, delay, distortion, and stereo panning to create entirely new sounds — from floating ambient pads to chaotic glitch textures. Powered by the Web Audio API, everything runs locally in your browser. Your audio is never uploaded. No DAW or plugins needed.
Upload an audio file or select a preset to begin
MP3, WAV, FLAC, OGG, AAC supported
About This Granular Synthesizer
SoundTools.io Granular Synthesizer is a free browser-based tool that uses granular synthesis to transform any audio file into ambient textures, evolving soundscapes, and experimental compositions. Upload a song, a voice recording, a field recording, or any audio — the tool chops it into tiny grains (5–100 milliseconds) and recombines them with pitch-shifting, time-stretching, reverb, delay, and distortion to create entirely new sounds. Everything runs in your browser using the Web Audio API. No plugins to install, no DAW required, no account needed. Your audio never leaves your device.
What Is Granular Synthesis?
Granular synthesis is a sound synthesis technique that works by splitting audio into tiny fragments called "grains" — typically 5 to 100 milliseconds long — and then reassembling, overlapping, and transforming them to create new sounds. Each grain is like a tiny snapshot of the original audio. By controlling parameters like grain size, density (how many grains play per second), playback position, pitch, and scatter (randomness), you can create an enormous range of sonic textures — from smooth, cloud-like ambient pads to chaotic glitch storms, from frozen vocal textures to shimmering crystalline drones.
How Granular Synthesis Works
The process follows these steps: First, source audio is loaded — any audio file becomes the raw material. Then a region is selected — you choose which part of the audio to granulate. Grains are extracted — the engine continuously slices tiny fragments from the selected region. Each grain can be pitch-shifted, reversed, scattered to different positions, or stretched. Overlapping grains create a new continuous sound texture, and effects like reverb, delay, distortion, and panning shape the final output.
Granular synthesis was pioneered by composer Iannis Xenakis in the 1960s and developed further by Curtis Roads, Barry Truax, and others. Today it is widely used in electronic music production, film sound design, and experimental composition. Popular granular synthesis tools include Ableton's Granulator II, Baby Audio's Grainferno, Output's Portal, and accSone's crusher-X — all of which are desktop applications or DAW plugins. SoundTools.io brings granular synthesis to the browser for free.
How to Use the Granular Synthesizer — Step by Step
- Upload or Choose a Preset: Click "Upload Audio" to load any audio file (MP3, WAV, FLAC, OGG) or pick a preset from the dropdown. Presets load a sample with optimized settings for that sound — like "Ambient Cloud" for dreamy pads or "Glitch Storm" for chaotic textures.
- Select Your Sample Zone: The waveform shows your loaded audio. Drag the highlighted region handles to select which part of the audio you want to granulate — or use the entire file.
- Click Play and Interact: Hit Play to start the granular engine. Move your mouse or finger on the XY Grain Canvas — the X axis controls where grains are pulled from, and the Y axis controls pitch. When you stop interacting, the tool auto-drifts through the audio, creating continuously evolving generative textures.
- Adjust Parameters: Use the sliders to dial in grain size, density, scatter, pitch, speed, pan, reverb, delay, and distortion. Toggle forward/reverse for different grain directions.
- Record and Download: Click Record to capture your output, then Stop to finish. Click Download to save your creation as a WAV file.
How SoundTools.io Compares to Other Granular Synthesizers
| Feature | SoundTools | Grainferno ($99) | crusher-X ($159) | ZYA Web |
|---|---|---|---|---|
| Price | ✅ Free | $99 | $159 | ✅ Free |
| Runs in browser | ✅ | ❌ Plugin | ❌ Plugin | ✅ |
| No install required | ✅ | ❌ | ❌ | ✅ |
| Effects (reverb, delay…) | ✅ | ✅ | ✅ | ❌ |
| Presets | ✅ 6 presets | ✅ 325 | ✅ | ❌ |
| Export / download | ✅ WAV | ✅ via DAW | ✅ via DAW | ❌ |
| Generative auto-play | ✅ | ⚠️ Limited | ✅ | ❌ |
| Mobile support | ✅ | ❌ | ❌ | ⚠️ |
What You Can Create
Ambient Textures & Pads
Transform any audio into floating, cloud-like ambient textures. Upload a piano recording, a guitar strum, or even a spoken word clip — granular synthesis stretches and layers tiny fragments into continuous, evolving pads perfect for ambient music, meditation backgrounds, or film scores.
Sound Design & Foley
Create unique sound effects and textures for film, games, podcasts, and video. Granulate metal impacts for sci-fi atmospheres, process nature recordings into alien landscapes, or transform everyday sounds into something completely otherworldly.
Experimental & Glitch Music
Push audio to its limits with tiny grain sizes, extreme pitch shifts, and high scatter values. Turn drum loops into stuttering glitch patterns, stretch vocals into eerie frozen textures, or create chaotic noise compositions from any source material.
Lo-Fi & Vaporwave Production
Granular synthesis is a key technique in lo-fi and vaporwave music. Slow down samples, add warmth with subtle distortion, and create that characteristic degraded, nostalgic feel from any audio source.
Learning & Education
Understand how granular synthesis works by hearing it in real time. The visual grain canvas shows exactly what's happening — each dot is a grain being played. Perfect for music technology students, educators, and anyone curious about digital audio processing.
Generative Music & Installations
The auto-drift feature means the tool creates continuously evolving music on its own. Record hours of unique ambient audio for installations, background music, sleep sounds, or creative inspiration.
Frequently Asked Questions
What is a granular synthesizer?
A granular synthesizer is a tool that uses granular synthesis to create new sounds from existing audio. It splits audio into tiny fragments called grains (typically 5–100 milliseconds long) and reassembles them with modifications like pitch-shifting, time-stretching, and randomization to produce textures, pads, drones, and experimental sounds.
How do I use this granular synthesizer?
Upload any audio file or select a preset, then click Play. Move your mouse (or finger on mobile) over the XY pad to control the sound in real time — the X axis controls which part of the audio the grains come from, and the Y axis controls pitch. Adjust the sliders for grain size, density, effects, and more. Click Record to capture your creation and download it as a WAV file.
Is this really free with no limits?
Yes. There are no usage limits, no account required, no watermarks, and no time restrictions. The granular synthesis engine runs entirely in your browser using the Web Audio API — there are no server costs.
Does this upload my audio to a server?
No. All processing happens locally in your browser. Your audio files are never uploaded anywhere. This tool is 100% client-side.
What audio formats can I use as source material?
You can upload MP3, WAV, FLAC, OGG, and AAC files. Any format your browser can decode will work.
Can I use this on my phone?
Yes. The tool works on mobile browsers (Chrome and Safari on iOS and Android). Performance is best on desktop, but all features are available on mobile including the touch-interactive XY pad.
What is the XY pad for?
The XY pad is the main interactive control. Moving your mouse or finger across it controls two parameters simultaneously: the X axis controls where in the audio file grains are pulled from (scan position), and the Y axis controls pitch. The animated dots represent individual grains being played. When you stop interacting, the tool auto-drifts through the audio, creating continuously evolving generative textures.
What do the presets do?
Presets load a sample audio file and set all the synthesis parameters to create a specific type of sound — like "Ambient Cloud" for dreamy pads or "Glitch Storm" for chaotic rhythmic textures. They're a great way to hear what's possible and start experimenting.
How do I record and download my creation?
Click the Record button to start recording the audio output. When you're done, click Stop. Then click Download to save your creation as a WAV file.
Do I need a DAW to use granular synthesis?
No. Traditionally, granular synthesis required a DAW and a plugin. SoundTools.io Granular Synthesizer runs entirely in your browser — no DAW, no plugins, no installation needed.
What is the difference between grain size and density?
Grain size is how long each grain lasts (5–100 milliseconds). Density is how many grains play per second. Small grains with high density create smooth, dense textures. Large grains with low density create a more sparse, choppy sound.
What does scatter do?
Scatter controls how randomly grains are positioned around the scan point. At 0, all grains come from exactly the same spot. At maximum, grains are pulled from random positions across the entire sample zone, creating a more chaotic, textured sound.
Can I create ambient music with this tool?
Absolutely — that's one of its primary use cases. Load any audio source, set large grain sizes, low density, add reverb and delay, and the tool will generate continuously evolving ambient textures. The generative auto-drift feature means it creates unique ambient music even when you walk away.