user5848: I would like to make a YouTube video that has a music visualizer on it (like in Monstercat videos), but I don't want to have to pay for After Effects. Is there a free way to do it? I know I can get the trial, but I want to be able to use it more than 30 days from now. Also, I'm using OS X, so whatever it is can't be Windows only.

user5546: According to the this article, iTunes has a music visualizer. You would still need to get screen recording software (unless you want to point a camera at your monitor!). I'm sure that someone has asked about free screen recording software on this forum somewhere.

user2836: Another idea would be to use something like Fraps or some other screen capture or screen casting utility to capture the playback of a visualizer in a music player of your choice.  The exact combinations of software to use would likely depend on your choices in music player though.
I know Fraps will only work with ones that are DirectX based.

user1950: Processing can do it, if you're not afraid of Java. There's a demonstration processing sketch that comes included with the application that does a frequency spectrum bar graph. It's relatively easy to save the output of a processing sketch to a video file. And it's free.

user6928: It's possible to screen record on macs for free using the program quick time. All you need to do is select File -> New Screen Recording and then you're good. 
You can use this with any normal full screen visualizer of your choice.

user17639: For simple music visualization videos for YouTube, you could check out https://www.musicvideodispenser.com.
It automatically generates a finished video based on an mp3 file you provide.
Disclaimer: I'm one of the creators of the service.

user18900: A free Alternative for After effects(for audio spectrum like in Monstercat) 

http://soniccandle.sourceforge.net

would be Sonic Candle.Its an open source project.You will need Java version 8 or higher in order to run.Best feature is the customizable bar visualizers.
Best alternative recommended is Rainmeter .You can add the Monstercat Visualizer by Marco Pixel Downloading from here.Just add it and customize to the way you want.
Pros:

Customizable
Quick & Easy

Cons:

No export option
You will need an extra monitor or you will have to hide all the icons when streaming or monitor capturing(The only choice)

Recommended: You can Screen capture the rainmeter(Saves time than rendering time in AE).

user26475: You can add a music visualizer to videos for free online using VEED. (Disclaimer, I am the developer of this software)




user3295: A free alternative for After Effects is Jashaka. It runs on every plattform and has some decent features. While it wont have the comfort of after effects for creating such an effect its certainly possible.
If you just don't want to spend all that much but still willing to pay a small price you can go for Apple Motion which costs 50$ and is a fairly powerful tool for animation and motion graphics for the price.
https://www.apple.com/final-cut-pro/motion/
Also here a tutorial on how make something react to music in Apple Motion: http://www.larryjordan.biz/motion-5-make-audio-move-video/
I personally have not worked in detail with both software so I can not give you guidance for actually creating the animation, expect for this tutorial.

user5671: Quartz Composer is free part of the apple developer kit. this can allow you to create music visualizers. In fact, the music visualizers that are defaulted in itunes are quartz composer files.

user18671: It's possible create using blender, watch this:




5848: <p>I would like to make a YouTube video that has a music visualizer on it (like in Monstercat videos), but I don't want to have to pay for After Effects. Is there a free way to do it? I know I can get the trial, but I want to be able to use it more than 30 days from now. Also, I'm using OS X, so whatever it is can't be Windows only.</p>
 5546: <p>According to the <a href="http://neomam.com/infographics/9-awesome-music-visualizations/" rel="nofollow">this article</a>, iTunes has a music visualizer. You would still need to get screen recording software (unless you want to point a camera at your monitor!). I'm sure that someone has asked about free screen recording software on this forum somewhere.</p>
 2836: <p>Another idea would be to use something like Fraps or some other screen capture or screen casting utility to capture the playback of a visualizer in a music player of your choice.  The exact combinations of software to use would likely depend on your choices in music player though.</p>

<p>I know Fraps will only work with ones that are DirectX based.</p>
 1950: <p><a href="http://processing.org" rel="nofollow">Processing</a> can do it, if you're not afraid of Java. There's a demonstration processing sketch that comes included with the application that does a frequency spectrum bar graph. It's relatively easy to save the output of a processing sketch to a video file. And it's free.</p>
 6928: <p>It's possible to screen record on macs for free using the program quick time. All you need to do is select File -> New Screen Recording and then you're good. </p>

<p>You can use this with any normal full screen visualizer of your choice.</p>
 17639: <p>For simple music visualization videos for YouTube, you could check out <a href="https://www.musicvideodispenser.com" rel="nofollow noreferrer">https://www.musicvideodispenser.com</a>.</p>

<p>It automatically generates a finished video based on an mp3 file you provide.</p>

<p><strong>Disclaimer:</strong> I'm one of the creators of the service.</p>
 18900: <p>A free Alternative for After effects(for audio spectrum like in Monstercat) </p>

<blockquote>
  <p><code>http://soniccandle.sourceforge.net</code></p>
</blockquote>

<p>would be <strong>Sonic Candle</strong>.Its an open source project.You will need Java version 8 or higher in order to run.Best feature is the customizable bar visualizers.</p>

<p>Best alternative recommended is <a href="https://www.rainmeter.net" rel="nofollow noreferrer"><strong>Rainmeter</strong></a> .You can add the Monstercat Visualizer by Marco Pixel Downloading from <a href="https://github.com/MarcoPixel/Monstercat-Visualizer/releases/tag/1.6.0" rel="nofollow noreferrer"><strong>here</strong></a>.Just add it and customize to the way you want.</p>

<p>Pros:</p>

<ul>
<li><p>Customizable</p></li>
<li><p>Quick &amp; Easy</p></li>
</ul>

<p>Cons:</p>

<ul>
<li>No export option</li>
<li>You will need an extra monitor or you will have to hide all the icons when streaming or monitor capturing(The only choice)</li>
</ul>

<p><strong>Recommended:</strong>  <em>You can Screen capture the rainmeter(Saves time than rendering time in AE).</em></p>
 26475: <p>You can add a <a href="https://www.veed.io/music-visualisation" rel="nofollow noreferrer">music visualizer to videos</a> for free online using VEED. (Disclaimer, I am the developer of this software)</p>
<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/N9bAWV5M3OI?start=0"></iframe>
            </div></div></p>
 3295: <p>A free alternative for After Effects is <a href="http://www.jahshaka.com/download/" rel="nofollow noreferrer">Jashaka</a>. It runs on every plattform and has some decent features. While it wont have the comfort of after effects for creating such an effect its certainly possible.</p>
<p>If you just don't want to spend all that much but still willing to pay a small price you can go for Apple Motion which costs 50$ and is a fairly powerful tool for animation and motion graphics for the price.
<a href="https://www.apple.com/final-cut-pro/motion/" rel="nofollow noreferrer">https://www.apple.com/final-cut-pro/motion/</a></p>
<p>Also here a tutorial on how make something react to music in Apple Motion: <a href="http://www.larryjordan.biz/motion-5-make-audio-move-video/" rel="nofollow noreferrer">http://www.larryjordan.biz/motion-5-make-audio-move-video/</a></p>
<p>I personally have not worked in detail with both software so I can not give you guidance for actually creating the animation, expect for this tutorial.</p>
 5671: <p>Quartz Composer is free part of the apple developer kit. this can allow you to create music visualizers. In fact, the music visualizers that are defaulted in itunes are quartz composer files.</p>
 18671: <p>It's possible create using blender, watch this:
<div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/JDaSk2mX7HU?start=0"></iframe>
            </div></div></p>
