 The Collective Optimization Database is an open repository to enable sharing of benchmarks, data sets and optimization cases from the community, provide web services and plugins to analyze optimization data and predict program transformations or better hardware designs for multi-objective optimizations based on statistical and machine learning techniques provided there is enough information collected in the repository from multiple users.The Collective Optimization Database is also intended to improve the quality and reproducibility of the research on code and architecture design, characterization and optimization.It includes an online machine learning-based program optimization predictor  that can suggest profitable optimizations to improve program execution time, code size, or compilation time, based on similarities between programs.