Most audio interfaces work great with JackTrip. We recommend using external USB or Thunderbolt interfaces for the best quality, low latency and glitch-free sound. Windows users must use an audio interface that provides ASIO drivers.
If you live within the United States, we strongly recommend contacting a Sweetwater sales representative. They are well trained to match your needs with the best audio gear available.
I believe all Macs still have 3.5” analog audio jacks built-in, and I would recommend using that with any analog wired headphones you have laying around to start. The built-in microphone on Macs is also perfectly fine for testing.
When you are ready to upgrade to better sound, you can’t go wrong with a Focusrite Scarlett external USB device, with the 2i2 model being a reference that most others are compared to. Their solo model is good enough for most people who don’t need the extra inputs. Sweetwater also offers some Scarlett bundles, and their sales reps are the best people to talk with about audio gear selection (better than me). UA’s Volt devices are also great, and Presonus’ AudioBox Go and ESI’s Neva Uno are also great devices at a lower cost.