Joe Taylor, K1JT, started it with WSJT (Weak Signal JT). then WSJT-X, then …

read it here: https://en.wikipedia.org/wiki/WSJT_(amateur_radio_software)

With FT8, you're restricted to very small messages, with a limit of 13 characters per message. Each message of up to 13 characters takes 13 seconds to send. There are 4 slots per minute, and you transmit for one 15 second block, then listen for replies for 15 seconds, and transmit again for 15 seconds.

FT8 Frequencies
Band	Frequency MHz	Notes	
30m	10.136		
20m	14.074		
20m	14.078	JS8Call	
20m	14.090	Region 1	

How much power does ft8 mode use? The general opinion is that FT8 is a weak signal mode but not a low power mode, ~20 watts is common for world wide contacts.

https://www.physics.princeton.edu//pulsar/K1JT/wsjtx-doc/wsjtx-main-1.8.0.html

FT-8 designed for fast QSOs, not much text exchanged, no keyboard-to-keyboard. only stored “brag tape”.

That lead to ::: FT8Call …. became known as    JS8Call

http://js8call.com … download software from there.

JS8Call is a derivative of the WSJT-X application, restructured and redesigned for message passing using a custom FT8 modulation called JS8. It is not supported by nor endorsed by the WSJT-X development group. While the WSJT-X group maintains copyright over the original work and code, JS8Call is a derivative work licensed under and in accordance with the terms of the GPLv3 license. The source code modifications are public and can be found in js8call branch of this repository: https://bitbucket.org/widefido/js8call/

JS8Call is and will always be open-source and free software (free as in beer and free as in speech, do with it what you like, for sum of exactly $0).

Why is this named JS8Call? Why was it renamed from FT8Call? It is named this way as an homage to its heritage:
	•	JS8Call was previously named FT8Call.
	•	JS8Call uses a custom FT8 modulation called JS8 (Jordan Sherer designed 8-FSK modulation). This is the base RF transport.
	•	JS8Call has a “directed calling” protocol laid over top the base RF transport to support free-form and directed message passing.
	•	
Hence JS8 + Directed Calling = JS8Call. And in case you didn’t get that:
The app is: JS8Call, the mode is: JS8

But wait, there’s more:
https://askinglot.com/what-frequency-is-ft8

JS8Call comes in a variety of builds.
	•	Desktop Linux (64-bit x86_64, deb)
	•	Desktop Linux (32-bit i386, deb)
	•	Raspbian Stretch (armv7, deb)
	•	Windows 10 (win32_64)
	•	Windows 10 is the only officially supported Windows build at this time, but the application has been confirmed to work all the way back to Windows XP.
	•	Mac OSX 10.11+ (x86_64)