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Music Prototyping Plugin by MusicDevelopments
Chord suggestions
Smart phrases Phrase generators Motive editing and generation Idea Tool Docked browsers Chord selection UI themes
RapidComposer by MusicDevelopments is a Virtual Instrument Audio Plugin and an Audio Plugin Host and a Software Application for macOS and Windows. It functions as an Audio Units Plugin, a VST 3 Plugin and a Standalone Application. It can host VST Plugins and VST 3 Plugins.
•Supported operating systems: Windows 8/10/11 (64-bit)
•Intel/AMD processor 1.4 GHz minimum
•512 MB RAM
•macOS 10.13-14 (latest update)
•Apple Silicon or Intel Core Duo minimum
Can Host
Can Host
Sample Formats
Loads and/or Saves
AIFF, SF2 (SoundFont), WAV
Copy Protection
Serial Number
My KVR - Groups, Versions, & More
187 KVR members have added RapidComposer to 74 My KVR groups 229 times.
Not In Your MY KVR Groups
(or group limitation prevents versioning)
+73 in private groups

KVR Rank

Overall: 722   564   707

30-Day: 1262; 7-Day: 1067; Yesterday: 495

RapidComposer is a rapid music prototyping software designed for composers, song-writers and musicians of all musical styles.


  • Unique non-destructive, phrase-based music composition.
  • Advanced tools for phrase editing, phrase morphing, phrase generation, phrase grouping, motif development, chord progression editing.
  • Chord suggestions, chord progression generation, chord progression rules editing.
  • Melody generation, melody harmonization.
  • Timeline with chords (absolute or chord functions) which all phrases automatically conform to.
  • Piano roll with scale notes, visually editable chord notes, and smart arranging of overlapped notes in two styles.
  • In-place non-destructive phrase-level and note-level editing.
  • Sophisticated MIDI CC editing and recording.
  • Articulations can be assigned to phrases or even individual notes.
  • Extensive scale, chord, guitar chord, chord progression databases.
  • Movable, resizable and transposable smart phrases that always conform to the current chord.
  • Phrase and rhythm generators help you to create thousands of musically useful (not random) phrases.
  • Taggable instrument library of all MIDI, VST/VST3 and SF2 presets in one place.
  • Variations can be applied to phrases, or whole tracks.
  • IdeaTool that can generate a multitrack composition based on the provided parameters and rules.
  • Intuitive drag and drop environment (you can drop chords, progressions, phrases, instruments to the composition).
  • Fully customizable user interface with preset themes.
  • Unlimited undo and the ability to make several versions of the same composition.
  • MIDI drag-and-drop tracks or composition to DAWs.
  • Virtual instruments and effects (VST/VST3 plug-ins) support.
  • SoundFont (.SF2) support.
  • Standalone and plug-in version (VST3 64-bit on Windows, AU and AU MFX on macOS).
  • Available for Windows and macOS (both Apple Silicon and Intel).

Products similar to RapidComposer...

Comments & Discussion for MusicDevelopments RapidComposer

Discussion: Disabled
6 June 2013 at 12:18am

Where are the (three) YouTube videos Chris was planning to produce ??

- atonal.

7 June 2013 at 7:13am

It sounds cool. Same thing on Windows ?

12 June 2013 at 2:45pm

Well all I can say about it was that (on my venerable iMac running snow leopard) the demo version kept crashing before I could see what it was about .....

1 July 2013 at 6:32pm

Pretty damn crashy on my Win8 laptop.

Luckily it autosaves before it crashes.

3 August 2013 at 11:36pm

Hi tommyzai, I agree with you concerning the concept of this software, but sadly rapid composer is unusable for me, buggy as hell, unstable...c'ant use it more than 5 min without problems! I have seen you are on Mac like me, please can you tell me what OS you use? I' m on mountain lion my computer is a Mac book pro quad core I7 end 2011. My vote is 10 for the concept and 2 for the reliability...

Best Regards.

1 April 2016 at 4:42am

Hi Chandran, I am so sorry I never replied to you. I had notifications turned off by mistake. I just happened to peek at my user review and found your inquiry. I hope the latest update of RC is running smoother for you. I have not had many freezes or crashes, and I've used it from Snow through El Capitan. I also have a i7 2011, but a MacBook Pro. It could be a conflict with other things, or I've just been lucky. Others have mentioned instability with early versions of RC. Hopefully, whatever it is. .. it's now fixed. It's a cool app and very useful. Tommy.

12 December 2013 at 7:27pm

Yes, it does seem a bit unstable. I sent an email with bugs I found, and Attila seems very keen on perfecting his software.. Just keep saving... Logic went thru quite a 'buggy' stage at one point (years ago). I'm using a MacPro 2008 (intel) OS X 10.7.5.

6 May 2014 at 12:57am

The manual on page 6 says: "CUSTOM MIDI FILES, SAMPLE COMPOSITIONS, and AUDIO SAMPLES are available for download for Demo & Registered versions.

Where exactly are these?

7 May 2014 at 8:57am

This is not too exact in the manual. The sample compositions can be found in the program as templates (click on the 'Using' menu next to 'New Composition').

Registered users get about 250 very usable phrases, and you can find hundreds of additional phrases on the support forum here at KVRAudio that can be used in the demo version as well. These are mainly strings staccato and piano phrases.

If you want to listen to songs created with RapidComposer, you will find them in this topic:


7 May 2014 at 12:43pm

Thanks for the quick response. After finding this forum and seeing it so un-used I was about to write RapidComposer off. I did find the link you provided (before you sent it), and after listening to songs I realized I really want to check RapidComposer out.

Just a suggestion ... in the kva forum there was no indication that I was actually in a forum about RapidComposer until I got into some posts. I would suggest that somewhere in the forum headers you make if obvious which areas are about RapidComposer. Once you know it if's find but for newbee's ... they might miss out on checking RapidComposer out.

7 May 2014 at 3:32pm

Yes, purposed to the visitors and the newbyes, simply change the header of the forum.

from "musicdeveloments"

to "MusicDevelopments RapidComposer"

would be an excellent idea to better identify the forum.

(who composes now exclusively on RapidComposer since last december)

7 May 2014 at 4:27pm

You are both right, but I cannot change the forum title because that should be the company name...

7 May 2014 at 3:56pm

Yes, this discussion is not really used. The open support forum has lots of interesting topics:


In addition some comments here are outdated, e.g. the OS X version is very solid now. The work on RapidComposer is continuous, bugs are fixed in very short time, and the forum is full of creative people. Registered users can try the latest beta version and use features weeks before the release.


5 May 2016 at 9:51pm

I just wrote a new user review based on the beta of v3. I hope users and potential users find my words useful.

5 May 2016 at 11:17pm

Very good review, Tommy! I would have added just another point at the end: Attila, the developer, is one of the kindest and of the most communicative guys in the world, and present IN PERMANENCE within his beta testers to have the most reactive returns and the best way to make the tool enhance permanently. Remarks, alerts, suggestions, engine, harmony rules, GUI... everything is discussed all together (and always in the best ambiance) to help Attila in his wonderful but very hard work. A bug found during the beta tests and confirmed by another tester or by Attila is generally fixed within the next days when not in the next hours! And we are a very active and a very enthusiast team around him. In my opinion, RapidComposer is now for the piano-roll what Sibelius or Finale are for the classical score writing, and nobody has gone as far as Attila in the quality concerning piano-roll writing and in the incredible sum of features to compose for the modern music as well as for the classical music, jazz music, rock music, ambient and chillout music, ethnic music (even for Asian, Indian, African, Arabic scales), songs, etc. Not only composing with RapidComposer is a true pleasure but contributing to his team of testers is one of the most pleasant times I have known in my life, now close to 60 years.

BlackWinny, who composes EXCLUSIVELY with RapidComposer since December 2013, the tool being used simply as a VST in my DAW to drive at its outputs all my instruments, each one on its MIDI channel.

5 May 2016 at 11:38pm

I'm honored to join such an amazing team of dedicated users.

6 May 2016 at 1:52am

Another decently-written review. It looks like we use some of the same music programming tools, despite being users of different platforms: you on OS X, and I on Windows.

6 May 2016 at 2:26am

tonedef71, thanks for appreciating my efforts. We're in it together. .. using tools to compose. .. looking for a better way.

6 May 2016 at 3:29am

Indeed. I couldn't have said it better myself. :)

Discussions have been disabled for this item.