Web ABX tester

Choose sample: By samples By file input

Status: ...
Score: ...
Probability of guessing: ...

This is a web-based ABX blind-testing tool. I think it's safe to say it's the first online ABX testing tool that doesn't rely on browser plugins.

Warning: this tool uses a lot memory to load the files. The audio data of both tracks is loaded completely into memory as raw PCM audio. This uses a few hundred MBs for a moderate song.

This web application uses the new Web Audio API. As of Febuary 2015, Chrome and Firefox work, Safari is not tested. See Support below for more information.

I made it because I wasn't satisfied with the ABX tester that came with Foobaar2000. It makes cliking noise when changing tracks and has a small but (to me) irritating gap. So I made my own. The way I prevented the same issues in the Web Audio API was by playing both streams at the same time and muting one of them. When changing track, one is muted and the other is unmuted. That way, no clicking or gap is audible (to me), thus making testing easier. And I added a few of my own features (auto continue, full keyboard support). In my opinion, it is better than the standard ABX Comparator of Foobar2000.

Keyboard shortcuts

a b x y
Play that track
Guess which of the two the currently playing track (X or Y) is.
Ok - do the guess
s e
Set start or end position.
Reset start or end to the beginning or end of the track, respectively.


As of April 2015, Chrome and Firefox are supported (see caniuse.com for up-to-date information). Safari is untested and will probably not work because the feature is still behind a prefix.

Audio codec support varies greatly (per browser and OS). A list of supported codecs in this browser (may not include all supported codecs):

MP3: ...
AAC: ...
WAV: ...
OGG: ...

"Maybe" and "probably" are indeed what it says... There is no guarantee it can or can't play that type. Although you can assume that "probably" means the codec is playable. See the full list of supported codecs.

A more important issue is that of gapless playback. This application requires gapless playback otherwise the results might be inaccurate. While gapless playback is practically universally supported for the WAV file format, this hasn't been implemented for most codecs. See Chrome bug #135291 and Firefox bugs #1129355 and #1130611.

Note: Chrome supports Opus playback, but does not yet support Opus in the Web Audio API. See bug #409402.