Mark Adler (born April 3, 1959) is an American software engineer. He is best known for his work in the field of data compression as the author of the Adler-32 checksum function, and a co-author of the zlib compression library and gzip. He has contributed to Info-ZIP, and has participated in developing the Portable Network Graphics (PNG) image format. Adler was also the Spirit Cruise Mission Manager for the Mars Exploration Rover mission.