ShareX

ShareX is a free, open-source screen capture powerhouse. Region capture, scrolling capture, screen recording to GIF/MP4, OCR text extraction, color picker, ruler, and automatic upload to 50+ destinations including Imgur and Dropbox. The workflow editor lets you automate post-capture actions. It's absurdly feature-rich for a free tool — the kind of app that makes you wonder why it doesn't cost money. Windows only.