'Distortion meter' is a wide category. A useful free tool for MacOS is LTspice, which runs on MacOS and Windows. It is of course a simulator, but it can be used to analyze the distortion of a circuit, as simulated through SPICE models of the components used in the circuit. And, of course, this is only useful if you're simulating an analog circuit.
If you're looking to measure an analog circuit, then a very wide range of hardware is available, with a wide range of price and capability. Likewise for devices in the digital domain.
Not trying to be a jerk, but what sort of device do you want to analyze? In the general case, there is nothing that does all of this well, but if you narrow the scope of your inquiry, there are probably a number of good solutions for your specific problem.