Contemporary research methodologies demand sophisticated multimodal data integration, requiring precise synchronization of video recordings with diverse temporal data streams. However, researchers often struggle with the technical complexities of aligning and analyzing these data sources, leading to inefficient workflows and potential errors in temporal alignment. We present a universal web-based labeling tool designed to streamline the synchronization, visualization, and labeling of multimodal data across various research contexts. The tool provides an intuitive web-based interface that integrates multiple video streams, sensor data visualization, and flexible event coding capabilities while maintaining millisecond-level temporal precision through Unix timestamp synchronization. Key features include dynamic window management for multiple video streams, real-time audio mixing, interactive sensor data visualization, and a customizable labeling system supporting both point and duration observations. We demonstrate the tool’s practical application through a behavioral research use case studying children with intellectual and developmental disabilities, highlighting its ability to manage complex multimodal data streams while maintaining temporal alignment and labeling accuracy. The tool’s web-based architecture eliminates platform dependencies and installation requirements, while its open source nature ensures accessibility across research communities. By providing a free, standardized solution for multimodal data analysis, our tool addresses a critical need in modern research methodology, enabling researchers to focus on generating insights rather than managing technical complexities.