ShareX is the most capable free screenshot tool available for Windows. It does everything CleanShot X does — and then some — at no cost. If you spend any time capturing or sharing content from your screen, this is the tool.
Capture modes include region, window, fullscreen, scrolling capture, and even screen recordings and GIFs. After capturing, you can annotate with arrows, boxes, text, and blur regions before sharing. There’s a built-in image editor and an OCR tool that reads text from any screenshot.
Sharing is equally well-covered: ShareX can automatically upload to Imgur, Google Drive, Dropbox, your own FTP server, or dozens of other destinations, and copy the link to your clipboard — all in one keystroke.