Purpose: Oncofertility counseling of female cancer patients lacks efficient access to tailored and valid infertility risk estimates to support shared decision-making on fertility preservation treatments. The objective was to develop, conduct user-centered design, and plan clinic-based implementation of the Cancer Related Infertility Score Predictor (CRISP), a web-based tool to support infertility risk counseling. Methods: Using a mixed methods design, literature review was undertaken to abstract data on infertility, primary ovarian insufficiency, and amenorrhea risks of common cancer treatments. The CRISP website was programmed to take user input about patient ages and cancer treatments and generate a risk summary. Using user experience methodology and semistructured interviews, usability testing and implementation assessment were conducted with 12 providers recruited from 5 medical centers in Southern California. Results: The web-based CRISP tool encompasses infertility risk data for 60 treatment regimens among 10 cancer types. Usability testing demonstrated that the tool is intuitive and informed minor modifications, including adding crowd-sourced submission of additional cancer treatments. Participants rated the tool as credible, advantageous over current provider methods to ascertain infertility risks, and useful for tailoring treatment planning and counseling patients. A key barrier was lack of information on some cancer treatments. Fit within clinical workflow was feasible, particularly with electronic health record integration. Conclusions: The novel, web-based CRISP tool is a feasible, acceptable, and appropriate tool to address provider knowledge gap about cancer related infertility risks and use for patient counseling. CRISP has significant potential to support tailored oncofertility counseling in the heterogeneous young cancer patient population.