Fully homomorphic encryption (FHE) extends traditional encryption schemes. It allows one to directly compute on encrypted data without requiring access to the decryption key. This paper introduces CONCRETE, an open-source library developed in Rust that builds on the state-of-art TFHE cryptosystem. It provides a userfriendly interface making FHE easy to integrate. The library deals with inputs of arbitrary format and comes with an extensive set of operations to play with ciphertexts, including a programmable bootstrapping. CONCRETE is available on GitHub at URL https:// github.com/zama-ai/concrete and on https://crates.io.