Use your arrow keys (up) while having chat open to access older messages you've sent.
You can use F5 in the server menu list, useful if you wanna check your ping
TAB autocompletes commands/minecraft username
Discord
⭐ CTRL+SHIFT+ALT+V Focus on the voice call you're currently in
⭐CTRL+SHIFT+A Minimalize all categorie, EXTREMELY USEFUL FOR CTT
⭐CTRL+SHIFT+I Opens Inbox, which filters all unreads/mentions through all servers/channels/DMs
CTRL+K in discord is very useful, just search whatever you wanna get to and press enter, way faster to get around
CTRL+R to completely reload Discord if it's broken or you messed up with it/wanna update it
SHIFT+ENTER to add a line while typing/editing a message
Middle click on an image will Open original image in your browser
CTRL+/ get a list of ALL discord keyboard combos
To quickly edit the last message you sent, press TAB, then UP arrow until your message is highlighted, and press E to edit, the same can be done for replying instead of editing by typing R
+:thumbsup: reacts :emoji: to latest message
Misc tip: you can expand a thread/forum post by clicking it's title at the top
Web browsers
CTRL+W to close the current browser tab (1000x faster than clicking the small x ) , CTRL+T to open a tab.
CTRL+SHIFT+T opens your last closed tab
CTRL+TAB, similar to Windows' ALT+TAB, this cycles through chrome tabs instead of windows the exact same way