The Codex Gigas is not a grimoire or a spellbook. It contains no instructions for summoning demons (aside from traditional exorcism rites). Its "evil" reputation stems solely from the Devil’s portrait.
You can view the through the Kungliga biblioteket (National Library of Sweden) website. It allows you to zoom in so close you can see the texture of the vellum (animal skin) and the ink stains. codex gigas pdf english
And when scholars centuries later searched for a public PDF—an image, a copy they could hold without risking their own names—they found many translations and scans, each with clear letters and luminous images. They could see the giant and the marginalia and read the recipes and the exorcisms. But none could capture exactly the tenor of the book's bargain: that knowledge, when gathered into a single body, may ask for payment in the coin of human memory—and that sometimes, if one is lucky, the trade can be made small and humane: one rooster for a man's mother, a single morning returned to the long ledger of a life. The Codex Gigas is not a grimoire or a spellbook