office-addin-validator

This was first released in 2016 and was last updated in 2017.
This was a command line tool that could be used to validate your manifest.
At the time this used the same validation service that the Office Store used.
This can only be used to validate manifest files that are saved on your local drive.
link - npmjs.com/package/office-addin-validator
link - github.com/officedev/office-addin-validator

Installation

Install the module by running the following command.

npm install -g office-addin-validator 

Validation

Once installed you can run it against a locally saved manifest file.

validate-office-addin manifest.xml 

If the script has been defined in the webpack.config.js file

npm run validate manifest.xml 

Yeoman Generator

Any add-ins created with the Yeoman Generator before October 2018 will have this dependency installed.

npm - manifest-validation

The beta version of this package had a different name.
This was last updated in 2016.
link - npmjs.com/package/manifest-validator