This is a certified implementation of a financial multi-party contract language. The Coq-based certified implementation of the language is found in the Coq subdirectory. The contract language and its verified Coq implementation are documented in the accompanying ICFP 2015 paper; the README file provides an overview of the Coq proofs. Moreover, this repository also includes earlier prototype implementations of the contract language in Haskell (see Haskell subdirectory) and Standard ML (see SML subdirectory).