keycastr/keycastr

KeyCastr is a small open-source Mac app that shows the keys you press on screen in real time. It is useful when you are recording a screencast, giving a live demo, or pairing with someone over a video call, because the viewer can see which keys you actually hit rather than just the result of those keys. You can choose to show only the command-key shortcuts, all keys with modifiers, or every keystroke, and there is an option to include mouse clicks as well. Installation is straightforward. You can grab a built copy from the GitHub releases page, or install it from Homebrew with brew install cask keycastr. Once it is running it shows the keystrokes in an overlay window on the screen, by default in the bottom-left corner. You can move the overlay by clicking and dragging the displayed text. Because the app needs to see every keypress, macOS will ask for permission before it works. On macOS 10.15 and newer it appears under the Input Monitoring section of the Security and Privacy panel in System Preferences, where you tick its box to enable it. On older versions, or if it does not show up automatically, the README explains how to add it manually under Accessibility instead. There is also a troubleshooting checklist for when the app appears to do nothing, which usually comes down to denied permissions or the overlay window being placed offscreen. The README addresses the obvious security worry. Any program with these permissions can see everything you type, so it tells you to look carefully at which apps you grant Accessibility or Input Monitoring access to. KeyCastr itself is open source, sends no data over the network apart from the Sparkle framework that checks for updates, and will not display the contents of password fields as long as the website or app marks them as such. KeyCastr has been available for the Mac since 2009 and is released under the BSD 3-Clause licence. The README credits the original author and several later contributors who took over maintenance, added a menu bar icon, and refreshed the application icon for newer macOS styles.