Mark Adler (born April 3, 1959) is an American software engineer, and has been heavily involved in space exploration. 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.