Ext, ext or EXT may refer to:
- Ext functor, used in the mathematical field of homological algebra
- Extended file system, a file system created for Linux; see also ext2, ext3 and ext4
- Ext (JavaScript library), a programming library used to build interactive web applications
- Exeter International Airport (IATA airport code), in Devon, England
- Extratropical cyclone, a mid-latitude cyclone
- Extremaduran language (ISO language code), spoken in Spain
- Extremeroller, a former roller coaster at Worlds of Fun, Kansas City, Missouri
- Cadillac Escalade EXT, a pickup truck