What is Slopsmith? The Open-Source Guitar App, Explained (and a Guided Alternative)

May 30, 2026by OpenFret Team

If you've been looking into software that listens to your real playing, you've probably hit the name Slopsmith. It's free, it's open-source, and it has a real following. The core idea is the good kind of simple: plug in, a note highway scrolls down the screen, and the app listens to what you play and tells you whether you nailed it.

This is a fair look at what Slopsmith is and who it suits, and then an honest pitch for OpenFret, which goes after a different job. Slopsmith is built for playing songs. OpenFret is built for learning the neck.

What Slopsmith actually is

Slopsmith is open-source software (AGPL-3.0) for practicing guitar with real-time note detection. It comes in two pieces. The web UI runs in a browser and gives you the song library, the scrolling note highway, and the note detection. The desktop app wraps that same UI and adds the heavy audio gear: it hosts VST3 and AU plugins so you can run amp sims like Neural DSP, ToneX, or AmpliTube, it has a built-in Neural Amp Modeler for free amp tones, it loads cabinet IRs, and it runs low-latency audio through ASIO on Windows or CoreAudio on Mac.

In plain terms, it turns your computer into a guitar rig and a play-along game at once. You bring a song, it scrolls the notes, you play, and your tone runs through whatever amp chain you've built. It's free, the community ships plugins for it, and it works on Windows, Mac, and Linux. For software nobody's charging you for, that's a lot.

Who Slopsmith is for

If you already know what you want to practice and you mostly want a better way to play it, Slopsmith is a strong pick. It's made for players who like tinkering with tone: loading amp sims, dialing in a signal chain, running a guitar through a Neural Amp Modeler. If you're comfortable installing open-source software and you want a local rig you fully control, it does that job well. I'm not going to talk you out of it.

What a note highway can't do for you

There's one thing a note highway can't do, though: tell you what to practice.

It shows you a song. You play the song. You get a little better at that song. That's real progress, but it's also how a lot of people spend years quietly plateauing, grinding the same five tunes and never actually learning the fretboard, the scales under their fingers, or why any of it works.

A player assumes you already have a plan. If you don't, and what you really want is to get better at guitar in an order that makes sense, you need a curriculum, not just a song to play over.

OpenFret: a guided curriculum that plays like a game

That's the gap we built OpenFret's Guitar Quest to fill. It listens to your real guitar through note detection, and it runs in your browser too. What's different is what happens after you plug in.

Instead of handing you a song, it hands you a path. You start at the beginning, practice scales and core concepts, level up, and the next thing to work on is always sitting right in front of you. It's organized like a course and it plays like an RPG.

There are six modes. In Battle you fight monsters by playing the right notes: hit the note, deal damage; miss, take the hit. Wisdom is high-rep drilling that burns the fretboard into muscle memory. Technique works sweep picking, string skipping, and position shifts. Magic has you running scales to earn enchantments for your guitar. Crafting turns loot drops into guitar parts, and Gigging sends you out to play shows for money and reputation. On top of the modes there are nine Arcade trainers, including scale runs, fretboard memory, chord sniping, ear training, and CAGED position shifts, and they're procedural, so you never run out of reps.

The XP and loot aren't just decoration. They're the part that gets you to come back tomorrow. Most people quit guitar because practice is boring and progress is invisible. Guitar Quest makes the progress something you can see and the practice something you'll actually do.

Slopsmith vs OpenFret: which one do you want?

It comes down to the job you're hiring the software for.

Go with Slopsmith if you want a free, open-source rig you install and own: a note highway plus a full tone setup with VSTs and amp sims, where you bring your own songs and your own plan.

Try OpenFret if your goal is to learn the neck and you'd rather follow a path than build one. It's guided, it's structured, and it keeps track of where you are.

On price I'll be straight with you. Slopsmith is free, since it's open-source and runs on donations. OpenFret's full game is $30 paid once, with no subscription, no ads, and no upsells. The demo is free and asks for no signup, so you can plug in and play before you decide anything.

Try the demo and find out

The quickest way to know if it clicks is to just play. Open the Guitar Quest demo, plug in (or let the built-in mic pick up an acoustic), and go. No download, no account, about a minute to your first note. If it's not for you, close the tab and you're out nothing.

Weighing it against the bigger names too? We wrote an honest comparison of Yousician, Rocksmith, and OpenFret.