There surely are tools to convert a recording to a higher level binary file. The one David linked to though seems to convert binary file to audio, which is the opposite direction.
ZX81TAP seems a bit convoluted, in that you would run a ZX Spectrum emulator with capacity to input audio in order to load a ZX-81 file that you can store as a snapshot or TAP file. I don't know how well it works. Perhaps the other tool TSCon3.3 is easier to use.
Here is a Java applet. The mention of Java gives me shudder along the backbone, but perhaps this is one of the small fraction of applets that actually works.
Here is a discussion thread that goes through a number of programs, their cons and pros and launches yet more software. Try it, you might like it!
I would assume some of the ZX-81 emulators can take WAV input as well without going through conversion first, but a specialized tool might be better at telling you if your file is mush or not.