A new open source mapping of IEC 61850-7-2 to web services has been defined and implemented. This letter describes work which is useful for rapidly implementing user interfaces—particularly web-based interfaces—for monitoring and controlling intelligent electronic devices from multiple vendors. The web service mapping has been implemented using the Hypertext Transfer Protocol, with a message format in JavaScript Object Notation. This approach requires a simple and ubiquitous software stack for its implementation, which is a significant advantage over existing client-server communications mappings. The use of an open source paradigm allows for the rapid iteration and refinement of the design, implementation, and testing of the internal details of the proposed protocol stack in a collaborative manner. These developments are of immediate interest to users of IEC 61850, and are particularly relevant to the IEC 61850 standardization process.