The Modified Checklist for Autism in Toddlers (M-CHAT) is an internationally validated tool for screening for autism spectrum disorder (ASD), based on a 23-question yes/no questionnaire to identify risks in children aged 16 to 30 months. In Brazil, the questionnaire, commonly administered by a healthcare professional in Basic Health Units (UBS) and APAEs (Association of Parents and Friends of Exceptional Children), faces significant challenges due to the manual paper-based process, which exacerbates waiting times and overburdens professionals. The objective of this work was to build and validate the "M-CHAT Digital" tool, a responsive web application accessible via mobile devices and computers, designed to automate screening and provide anonymized statistical reports via API for specialists. Validation was performed using questionnaires provided by APAE of the city of Feliz, comparing risk results with the M-CHAT Digital platform, as well as feedback from specialists at that institution. A user-friendly tool was developed for both parents and doctors, who can also quickly access real-time statistics using the query API. The tool significantly reduced screening time, eliminating the need for in-person attendance solely for administering the screening questionnaire. The tool preliminary feedback met expectations of specialists who previously administered the questionnaire manually, modernizing and facilitating the ASD screening process.