BoCaps

BoCaps lets you switch selected text between uppercase and lowercase with a double-tap of Caps Lock, in any Windows app. No menus, no shortcuts to memorize: select your text, double-tap Caps Lock, and it flips case instantly.

Works in Word, email, browsers, code editors, and anywhere else you type. The double-tap doesn't interfere with Caps Lock's normal behavior, and your text selection is preserved after the switch, so you can keep working right away.

BoCaps runs quietly from the system tray, with no extra windows to manage. It starts with Windows automatically, and you can adjust the double-tap speed to match your typing rhythm.

Completely free to use, with an optional way to support the developer if you'd like to.