Can anyone recommend a CW reader?

I'd be especially interested in a software one that ran on Linux, and
it would be wonderful if the source was available. I have the MFJ
device but it broke, and I'd prefer a software one, anyway (I like to
tweak sometimes).

Just in case someone wants to warn me against such devices: I read CW
by ear at about 15 wpm, but I'd like to improve my fist and I have
heard that the readers are good for that, as they only read well-formed
code.

Tnx, Jim KE1AZ