Roland TB 303 Emulator: a Free Online Virtual Synthesizer

Roland TB-303 Bass LineWhether you’re looking for a Roland TB 303 emulator or some other free online virtual synthesizer, you have definitely come to the right place. I want to help you get started making electronic music, so I have found some really great free music programs that you can use directly within your web browser. All you need is your computer, a connection to the internet, a web browser, and some speakers or headphones. That’s it!

Roland TB 303

You probably know what a TB-303 is, but if you don’t, here is a demonstration:

It’s a bass synthesizer that Roland made in the 80s. Well, they were originally designed to play traditional bass lines so that you could play guitar over the top, for example. However, people started using them to create that classic squelchy acid house sound instead.

These days you can pay a LOT of money for a second-hand TB-303. The thing is, though, you don’t need to.

Introducing Acid Machine: the Online TB 303 Emulator

Now you can use a free software version of the TB-303 from your web browser:

I know it doesn’t look exactly like the original TB-303, but it has many of the same controls. You’ve got saw and square wave, tune, cutoff, resonance, envelope mod, decay, accent, octave a slide. Actually, Acid Machine is more than just one TB-303. It features two of them, plus a drum machine too!

My only criticism is that it seems like the filter cutoff and resonance don’t go as extreme as they do on the real thing. Still, it’s free, so we can’t really complain too much.

You can have a play with it right now by visiting:

The awesome thing is, you can even save your sequences as wave files. So you could create a bunch of sequences then use them as loops in a free DAW like Audacity, for example.

But Wait, There’s More!

I’m not going to leave you with just one free toy to play with. No, I want to send you way with a big smile on your face, so here are some other free online synths that you can have fun with.


With this one, you can play the notes with the keys of your computer keyboard.

It has two keyboards, one for bass notes and one for treble notes. You can “record” yourself playing into the sequencer, and it can automatically quantize your notes to make them fit into a tight rhythm.

You can then use your mouse to adjust the various sound parameters. The filter cutoff and resonance can go quite extreme, into uncomfortable territory actually. Don’t push it to the max while your speakers are loud or you’re wearing headphones, or you might hurt your ears!

One thing I like is that using the LFO parameter you can get some great pulsing sounds. If you push it fast enough, you can get a really authentic sounding computer game effect as you can hear in this demonstration video:

Why not have a play with it yourself at:

Audiotool Tonematrix

This one is a bit different, in that it just consists of a matrix that you can click to add notes. It’s quite hypnotic actually, to see the visual representation of your notes:

Why not try it out for yourself at:

But notice what happens if you click the “Add Drums” button. You get taken to…

Audiotool Music Maker

This is a free online music making program which you can use directly in your web browser. You have a mixer, an arranger section, and then a bunch of drum machines, synths, tools, and effects, any of which can be dragged into the main area to be included in your music project.

And this brings us right back to the original topic of this post – Roland TB 303 emulators – because Audiotool has a TB 303 emulator built into it too!

Take a look:

Why not have a play around with it yourself at:


If you want to experiment with modular synthesis, why not take a look at the WebModular synthesizer. Unfortunately, I don’t have a video demonstration of this one, because nobody has made one yet. That must mean that not many people know about this online synthesizer yet.

It is a web browser version of a modular synthesizer. That means you can play around by linking different parts of different modules to each other to get weird and interesting sounds.

Why not have a play with it at:

So there you go, you not only have a free online Roland TB 303 emulator to play with; you also have a bunch of free online virtual synthesizers and drum machines to enjoy messing around with. It just goes to show, there are more and more free music making tools available these days, so nobody has any excuse not to get started making their own electronic music.

Please let me know whether you enjoyed these online music tools, or if you have any questions or comments. Even more importantly, if you have made any music using these free instruments, please post a link to them in the comments section. Put them up on SoundCloud or something. Even if they are just works in progress, I would still love to hear them. Maybe I can even help you develop them further?

Additionally, if you know of any other free online virtual synthesizers or music making programs that I could add to this list, that would be awesome.

All the best,

P.S. You may also be interested in this free online music composing software.


  1. hardkick

    Drum machines HTML 5 and HTML 909 do not work – links are broken.

    1. Marcus (Post author)

      Thanks for letting me know. I have removed them.


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