Mozilla Deep Speech is an open source speech recognition engine, based upon Baidu's Deep Speech research paper[2].
Unsurprisingly, Deep Speech requires a corpus such as... Common Voice.
[1] https://github.com/mozilla/DeepSpeech
[2] https://arxiv.org/abs/1412.5567
It also looks like Baidu are now developing their Deep Speech as open source? https://github.com/PaddlePaddle/DeepSpeech