Alex VE3NEA has been known for many years for programs for radio amateurs. In addition to well-known DX Atlas, CW skimmer, Ham CAP or Rocky (SDR), there are many others in his portfolio. One of them is freeware RTTY decoder, GRITTY.
This program was developed for the RTTY Skimmer Server, but unlike it, it decodes stations in the 3 kHz range fed into the audio input of the sound card. This is how its use looks like in operation:
An interesting function is the decoding of weak characters. Where the algorithm evaluates the signal as unreliable, the sign will be displayed in light color. This is not evaluated on the basis of signal strength, but on the assumption of error. For example, even an experienced operator can evaluate this in his head, but the software does it bit by bit using the Bayesian formula. If GRITTY captures the tag correctly, it will appear in the tag box. More about what is the advantage of this program at GRITTY demo page.
GRITTY also includes an API interface that allows it to be connected to other programs. Download is possible from the site https://www.dxatlas.com/Gritty