The Best Free Online Key and
Tempo Change Service 2020

Song Surgeon was the top ranked site on our list. This was because after a 2 half step change using our test music file there was NO distortion introduced into the file. Beyond this, the online tool is easy to use, tt allows you to change both key and tempo - and it allows changes in whole units - or in smaller increments, should that be necessary.

The step-by-step process on the Song Surgeon site allows you to preview your changes prior to processing your file. This allows you to hear the key or tempo change and to continue to change them and re-listen to make sure you have the key or tempo change that you need, before you process and download the file.

Lastly, after processing, the online tool allows you to select from among many different audio file formats before downloading your changed file.

The Twisted wave web page is a more complex system. One of the nice features is that, in addition to uploading files, you can use a URL to Google Drive or SoundCloud. While the sound quality after processing a file is good, it is not as good as Song Surgeon. It's biggest drawback is that it will process only a mono channel. You need to have a paid subscription to have stereo channel support.

One of the nice things about Conversion-Tool.com is the simplicity of the site. You upload your file and then choose from drop down boxes to alter your audio file. Though it offers two algorithms, both algorithms fail to process the test file without introducing some amout of distortion as key and/or tempo were changed. Lastly, there are sponsored ads on the site, that can be a distraction.

One of the strengths of the Audio Speed Changer site is that it supports a wide range of input file formats. On the flip side, the number of output file formats is limited to two: Mp3 and M4a.

Audio Speed Changeer provides what it calls a time-based and a frequency based method, but neither of these provide a clean, non-distortion file after processing. The test file, when processed using this tool, exhibits a distortion in the form of a wobble or tremor, that is not heard in the original file.

The Audio Trimmer site can only change the speed or tempo of an audio file. It Does Not change the key. This makes in much less useful that the others services that do both. In addition, like most other sites, when processing the test file it also introduced audio artifacts in the form of a wobble or tremor, making it less desirable. Lastly, there are a lot sponsored ads on the site, that can be a distraction.

The True Tone site is one of the easiest and most intuitive sites that we reviewed. One thing we really liked is that it has a typical audio player look and toggles to change key or tempo. Like other sites, it struggles to process our test file cleanly and introduced some distortion. It addition, perhaps its biggest drawback is that it only allows you to play the file on the site. It does not allow you to process these changes and create a new file that you can download and use off of the site.

The Tone Generator site has separate function for key change and tempo change. This is inconvenient because it means that you have to upload a file twice, and process it twice, if you need to change key and tempo in the same file. The conversion process is slow, the audio quality is average, and when we tested this site there were times when the processed file failed to download.

We attempted to use the Voice Changer site on two different occasions. It appeared to allow us to upload the file, but after that we could not get it to process the file. It is ranked here in last place primarily because the site is not working. If it were to be fixed, we could listen to the sound quality of the processed file and evaluate it against the other online services. However, at the time of our review the site was non-functional and therefore it lands at the bottom our our reviewed sites list.