The NASA Space Physics Data Facility (SPDF) announces the first public release of a comprehensive web-based metadata editor designed for the creation and validation of space physics data files compliant with International Solar-Terrestrial Physics (ISTP) guidelines. This browser-based tool enables mission teams and curation scientists to efficiently design and specify data file structures across multiple formats, without the need for any additional software. The ISTP metadata editor provides an intuitive interface for defining data file layouts for Common Data Format (CDF), netCDF (NC), CDF skeleton (SKT), and CDF JavaScript Object Notation (JSON) files, providing comprehensive coverage of common space physics data formats. Users can specify variable characteristics such as data types, dimensions, compression parameters, pad values, and fill values, while also defining both global and variable-specific attributes. The tool's flexibility accommodates files from local file systems or remote URLs, supporting diverse data management workflows. A key feature is the integrated compliance validation system, which verifies ISTP guideline adherence and supports custom validation through mission-specific XML configuration files. This capability allows teams to ensure formatting and metadata standards are met throughout the data file creation process. Additionally, the editor generates initial Space Physics Archive Search and Extract (SPASE) metadata XML files from the provided ISTP metadata. While these exports provide a foundational framework rather than complete SPASE records, they significantly accelerate the metadata documentation process by leveraging information already captured during data file specification. Cross-platform compatibility across major browsers (Chrome, Firefox, Safari) ensures broad accessibility of this tool/editor. This release represents a significant advancement in data file creation and validation tools, enabling more efficient metadata specification, compliance checking, and streamlined documentation workflows for space physics data management.