Are emojis free to use?

The Unicode characters themselves are free to type, copy, paste and share — they are part of the text standard, not owned by anyone.

The artwork (the PNG/SVG graphics that each platform ships) is copyrighted by the platform. You can't extract Apple's or Google's emoji images and use them commercially without permission. Open-source sets like OpenMoji, Twemoji, and Noto Emoji are usable under their licenses.