It shows every key you press in the bottom-left of Blender's 3D viewport, so the people watching a tutorial, short or livestream can see what you did. Combinations read as one press, repeats count up, and the mouse sits beside the keys and lights up as you click, roll and drag.

Yes. No price, no account, no licence key and nothing locked. It is GPL-3.0-or-later, from Tachyon Studio.

Blender 3.3 to 5.2, from one zip: an extension on 4.2 and later, a classic add-on on 3.3 to 4.1. It runs on Windows, macOS and Linux.

Click the Screencast Keys button at the very bottom of the 3D viewport's toolbar, on the left. It lights up while it is on. There is no sidebar tab and nothing else to open.

No. It only draws what you pressed on screen and forgets it a few seconds later. Nothing is saved, and it makes no network connection of any kind.

In the bottom-left of the biggest 3D viewport of each window, just above the TachyonSync light and clear of the toolbar. Lift in the preferences moves them up if something else sits in that corner.

Four ways, chosen under Mouse ▸ Show As in the preferences: Beside the Keys (the default, a bigger mouse that is always there and lights up), In the List (each click a row with a small mouse), As Text (LMB, MMB drag, Wheel ↑), or Off. Mouse Size sets how big the mouse beside the keys is.

Yes: Key Size, Rows, Show For, and the Text, Accent and Keys colours, all in the preferences. Show a Sample shows a change at once, and Tachyon Colours puts the house look back.

A running tool used it first. Keys typed while a tool is running, such as X, Y, Z or a number after G, and the click or Esc that ends it, go to that tool before the add-on hears them. The key that started the tool always shows.

Yes. Its button goes under every other tool in the toolbar, Hard Ops' included, and it reads keys without taking any of them.

No. It draws a few keycaps in one viewport, and only repaints while something on screen is fading or moving.