XMLSpy

XMLSpy is a proprietary XML editor and integrated development environment (IDE) for Windows developed by Altova. It provides comprehensive tools for creating, editing, validating, and debugging XML-based content and related technologies such as WSDL, XSLT, XQuery, and JSON.

The core editor supports multiple views—text, tree, grid—and includes schema-aware editing for XML Schema, DTD, and Relax NG. It offers syntax highlighting, code completion, and automatic validation as you type, along with visual schemas and diagramming. It includes built-in processors and debuggers for XSLT and XQuery, with support for evaluating expressions via an integrated XPath debugger.

In addition to XML, XMLSpy provides tools for working with Web services definitions (WSDL, SOAP), XSLT transformations, and XQuery queries. It can transform data between XML and other formats, and provides data mapping and database integration features to generate or consume XML from relational databases.

XMLSpy has been in development since the late 1990s and is distributed as part of Altova’s MissionKit suite of development tools. It is widely used in enterprise environments for XML development, data integration, and services design and testing. Licensing is commercial, with trial versions available.