What’s one business tool you can’t live without—but nobody talks about?

We always hear about the big names—Slack, Notion, Trello, etc.—but I feel like the most useful tools in business are often the quiet ones. The ones that just work, save time, and don’t need a 10-minute tutorial to figure out. I’m curious—what’s that underrated tool you use every day but rarely see mentioned? Could be a small Chrome extension, a no-code tool, a shortcut, or even a weird system you came up with on your own. I’ve personally found more value in low-key tools shared by real users than in most “top 10” lists online. So I figured I'd ask here and hopefully we all discover a few new gems. Drop your answer below—bonus points if you say why it works so well for you. Always looking for ways to make things smoother without overcomplicating the stack. Let’s build a thread of tools that actually make a difference.