Cadabra is a computer algebra system designed specifically for the solution of problems encountered in classical field theory, quantum field theory and string theory. The first version of Cadabra was developed around 2001 for computing higher-derivative string theory correction to supergravity. Released under the GNU General Public License, Cadabra is free software. A Java program inspired by Cadabra called Redberry was developed between 2013 and 2016. It achieved faster speeds for most index contractions with an approach based on the graph isomorphism problem rather than canonicalisation.