For engineers in need of performance models for complex systems, Collaborative and Rapid Engineering System-modeling Toolkit (CREST) is an innovative modeling and simulation tool that enables optimization and uncertainty quantification of physics based, multi-disciplinary computational models which will empower more comprehensive, broader, and deeper system and subsystem modeling. Unlike discipline-specific modeling that provides results for a single physical phenomenon (e.g. thermal, power, structural, dynamic, etc.), CREST provides advanced analysis results in near real-time. By expanding our existing innovative reduced-order modeling (ROM) approach (currently used at NASA JPL and MSFC), CREST will enable highly skilled engineers to more effectively explore complex, multi-disciplinary design spaces. CREST is an innovative modeling and simulation tool that will enable multi-disciplinary analysis capabilities that are currently unavailable using current technologies. Leveraging near real-time analysis capabilities, CREST will open the door to more effective multi-disciplinary analysis, optimization, and uncertainty quantification. These capabilities are not available using state-of-the-art methods. Potential NASA Applications (Limit 1500 characters, approximately 150 words) NASAs ability to make engineering breakthroughs can be limited by the ability to transform data into scientific and engineering knowledge through sophisticated means. CREST meets this need by providing a toolkit that enables fast, advanced-analysis for multi-disciplinary systems. Specific NASA applications include NASA JPLs Mars 2020 Helicopter mission and MASA MSFC lunar lander technologies. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) Due to CRESTs ability to integrate data from common, commercially available engineering packages, it is applicable to a wide range of applications and industries; it is relevant to any application that requires fast and advanced analysis of complex, multi-disciplinary systems. Potential customers include commercial manned spacecraft, Gov't agencies, and prime contractor and commercial developers.