Otto is your assistant for WSJT-X (the extremely popular amateur radio weak-signal digital modes program).
Click here > https://github.com/avantol/Otto/blob/main/Otto.msi (also listed above), then download 
and run Otto.msi to install.
At the Windows warning message, click "More info" then "Run anyway".
A modified WSJT-X is also required, download and run the installer wsjtx-v2.7.0-win64_MOD.exe at
https://github.com/avantol/WSJT-X_2.7.0/releases/tag/v2.7.0-185
Use all appropriate caution since transmit can start at any time once you select "Enable Tx" in WSJT-X!!! Whenever the "Enable Tx" button is red, your antenna can be energized.
At first run, basic mode:
Later, advanced mode:
As a start, Otto stores up calls that are interesting to you that come in while you're working another call, then replies to each in turn.
You can also do things like:
- call CQ, or listen for interesting stations (listening conserves bandwidth)
- reply exclusively and repeatedly to calls from "rare DX" stations and expeditions
- call "CQ DX" and ignore non-DX replies
- reply automatically to "CQ DX" from stations that are actually DX to you
- reply automatically to local or DX stations you haven't worked yet
- reply automatically to CQs from POTA stations
- reply automatically to multi-stream stations
- automatically detect and transmit on the clearest section of a congested band
- manually queue up any other interesting calls for automatic reply
- prioritize replies by distance, SNR, azimuth, or order received
- bypass WSJT-X's clunky way of skipping the grid message or using RR73
- skip replies to RR73 (since RR73 is defined as "roger and out")
- transmit multiple different directed CQs
- log as soon as 2-way signal reports are confirmed
- reply automatically to CQs directed to your state or country
- never miss a "late" 73 again... instead, it gets logged
- automatically start and/or stop transmitting at specified time(s)
- reply to new countries "by mode" (FT8, FT4, etc.)
- reply to countries that are new for a specific band in addition to new for any band
Tips:
Otto and the modified WSJT-X program run as a "versioned" pair, and Otto checks for the correct WSJT-X version when it starts. Be sure to download and install both programs!
If you already have another WSJT-X version installed: You can install the required (modified) WSJT-X 2.7.0 program in an alternate destination folder if you like. Neither WSJT-X version will interfere with the other, and they share the same settings and preferences... convenient!
When Otto is not running, the modified WSJT-X 2.7.0 "forgets" its modifications and runs like the standard unmodified version.
The UDP address/port for the WSJT-X "UDP Server" is detected automatically by Otto.
For best results inter-operating with other WSJT-X helper programs, set the WSJT-X "UDP Server" (Settings | Reporting tab) to address 239.255.0.0 and port 2237, with all "Outgoing interfaces" selected.
If you experience any problems with Otto, close all other programs that interface with WSJT-X, then re-open each one at a time to determine which one causes the problem.
It's best to use JTAlert in a passive mode, where it does not forward log data or control WSJT-X. This has caused problems for several users.
HRD is reported to not inter-operate well with Otto, when JTAlert is used to forward log data to HRD.
DX Aggregator is reported to conflict with the communication between Otto and WSJT-X.
Logger32 does not inter-operate with Otto, since it is (apparently) designed to "run" WSJT-X by itself.
To get QSOs with stations "per mode" (ex: work an FT8 station, and later allow working the same station using FT4), in WSJT-X on the "Colors" tab, select "Highlight by Mode".
Otto does not work for contests, since contests are designed as tests of skill, not automated assistance. Contest calls and modes are specifically and purposely ignored.
Otto is disabled when Hound is selected, since call traffic management is done properly by the Fox station.