Which tool validates YANG modules online?

The tool that specifically validates YANG modules online is the Yang Validator. This tool allows users to check the syntax and structure of YANG modules to ensure they conform to the YANG specifications. By providing an online platform, Yang Validator makes it easier for developers to test their YANG models without needing to install any software or configure a local environment. The validation process helps catch errors early and ensures compliance with standards, which is crucial for interoperability in network programmability.

While other options, like Pyang, Ydk-gen, and Ydk-py, are valuable tools within the broader ecosystem of YANG development and usage, they do not focus exclusively on online validation. Instead, Pyang is primarily used for YANG module validation and conversion, and Ydk-gen and Ydk-py relate more to generating code and working with YANG in the context of specific APIs and frameworks, rather than providing online validation capabilities.