Does unflavored coffee need a hechsher?

Answer: No.

Reason: Plain coffee, including decaf, does not pose a kashrut issue and does not need certification.

Source:

• Shulchan Aruch, Yoreh De’ah 112:6; Pri Chadash, Orach Chaim 49:5.
• Star-K: unflavored whole-bean, ground and instant coffee (regular or decaf) needs no hechsher.
• cRc: unflavored coffee beans are acceptable without certification.
• OU: instant coffee is assumed not to need a hechsher, but buying it with one is “good and prudent practice.”

Related questions:

• Does flavored coffee need a hechsher? Yes.
• Does plain black or green tea need a hechsher? No.

More from Rabbi Tahan: Kosher Without Borders: Coffee, Coolers, and More

References: Star-K, “Approved Without A Hechsher” list · cRc (askcrc.org), “Coffee beans, whole” · OU, “Coffee” (Kosher in the Factory)