Abstract In the building industry, building data such as objects and processes are described in Industry Foundation Classes (IFC) data model schema to support a neutral data exchange format for BIM tools interoperability. While IFC specification has been encoded in ifcXML format by buildingSMART to support XML-based data transmission, there is a lack of studies on the implementation of IFC specification using JavaScript Object Notation (JSON) serialization. JSON is a key-value style lightweight data exchange format that has higher parsing efficiency than XML and due to the inadequacies of XML, JSON has been widely used in Web applications, specifically in Asynchronous JavaScript and XML (AJAX) Web services. This paper highlights the need for JSON implementation of IFC specification and introduces ifcJSON Schema and its data content. The main objective of this study is to outline how IFC specification can be represented in JSON format. Therefore, the study explains the implementation of the IFC standard as a JSON schema to guide the creation of JSON documents. The ifcJSON documents can be used for web-based data transfer as an alternative to XML documents. Since current IFC specification release is IFC4 Add1, the implementation of ifcJSON4 schema is specified and guidelines for generating and validating ifcJSON documents are described. Additionally, this paper implements ifcJSON4 schema in a use case within the precast concrete domain by indicating the data content for a precast building element with its corresponding geometry representation, product placement, and owner history data. The analysis of results indicates that ifcJSON4 schema developed in this paper is a valid JSON schema that can guide the creation of valid ifcJSON documents to be used for web-based data transfer and to improve interoperability of Cloud-based BIM applications.