This ssh web client doesn't require credit card for the first week, but they do require that after the first week. Although you won't be charged for the first month. The authors said that they are open to discuss the future of the application...

Could you please elaborate on what problems are you having? Are you on the /signup url?

In Chrome browser on Windows and in Firefox and Chromium on Linux, the text on the /signup page is black. The background is black. That makes the text invisible.

Weird. The background on the signup form should be white. Could you maybe provide an image of what's happening?