Download BellyDSP

Free, for macOS and Windows. Install it once and it keeps itself up to date.

Download for macOS Latest release on GitHub Download for Windows Latest release on GitHub

All files, older versions, and checksums: releases on GitHub. Source for this version: on GitHub.

What you need

Mac	macOS 12 Monterey or later, on Apple silicon or Intel (one app for both)
Windows	Windows 10 or 11, 64-bit
Audio interface	Any interface with an instrument (Hi-Z) input, set to 48 kHz. BellyDSP runs only at 48 kHz, the rate NAM captures are trained at; at any other rate it stays silent and tells you why.
Something to listen on	Headphones or speakers plugged into the interface
Format	A standalone app. There's no plugin version yet.

The first launch

BellyDSP is free software from an independent developer, not signed with a paid Apple or Microsoft certificate, so both systems ask once before opening it. That's expected.

Mac

Open the .dmg and drag BellyDSP onto Applications. Run it from Applications, not from the disk image or Downloads, or it can't update itself.
Open it. macOS says it can't verify BellyDSP: click Done (not Move to Trash).
Open System Settings > Privacy & Security, scroll to the line about BellyDSP, click Open Anyway, and confirm with your password or Touch ID. Then open BellyDSP again and click Open.
Allow the microphone when it asks. That's how macOS names every audio input, your guitar included.
Set the interface to 48 kHz: in Audio MIDI Setup (Applications > Utilities), click the interface and set Format to 48,000 Hz.

Comfortable with Terminal? This one line replaces steps 2 and 3:

xattr -dr com.apple.quarantine "/Applications/BellyDSP.app"

You only do this once; updates don't ask again.

Windows

Run the -windows-setup.exe.
If Windows says "Windows protected your PC", click More info, then Run anyway.
Click through the installer. It installs just for you, so it doesn't need an administrator password.
Set the interface to 48 kHz in its own control panel, or in Settings > Sound > your device > Properties > Advanced.

Choosing the input

Click Options at the top of BellyDSP's window, then Audio/MIDI Settings:

Output and Input: your audio interface. Sample rate: 48000.
Active input channels: only the one your guitar is plugged into (usually Input 1).
Buffer size: 128 samples is a good start. Smaller feels more immediate; if you hear crackles, try 256.
Windows: pick the device type Windows Audio (Exclusive Mode) for the lowest delay.
Untick "Mute audio input". It starts ticked, as a guard against feedback, and you'll hear nothing until you untick it; a yellow bar says so.

On the interface: switch the guitar input to instrument (INST or Hi-Z), set the gain so your hardest strum stays out of the red, and turn Direct Monitor off, or you'll hear your dry guitar on top.

Updates

Once a day, while it's open, BellyDSP checks GitHub for a newer version. Every update is signed, and the app refuses one whose signature doesn't check out.

Mac: it downloads the update quietly and installs it the next time you quit. Nothing to click.
Windows: it asks first. Click Install update and it closes, updates, and opens again. You can also skip a version or be reminded later.

To see your version, or check right now, click BellyDSP at the top left of the window.

What's new

The release notes for every version are on GitHub's releases page.

Privacy

BellyDSP collects nothing about you, and neither does this site.

The app checks GitHub for updates about once a day while it's open. The request carries no account, no ID, and none of your settings: like any download, GitHub sees your IP address and the app's name and version.
GitHub counts how many times each release file is downloaded, anonymously, and anyone can see those counts. The stats page is built from them.
This site sets no cookies and runs no analytics or third-party scripts. Fonts and images are served from here.
Downloads and update checks go through GitHub, which runs its own servers and logs under its privacy statement.