Literally, XD, but written as how it is pronounced in Spanish ("equis" for X, "de" for D).
Some use it as a toned down variant (similar to the ending a sentence with "lol" instead of "XD"). Nowadays, some use to distance themselves from old-school meme speak that overused the emoticon (such as "xdxdxdxd" in memes from communities like SDLG). Some use it more in ironic shiposts. However, tbh, most normal people use "equisde" and "XD" indistinctly.