The Professional Licensing API is a RESTful API resource that allows API clients to request the status and other relevant data metrics associated to a professional contractor license. API clients submit a GET request through a simple API url which includes a "license number" path parameter. Associated data is returned through a json data response.

The API is designed to be implemented by vendors and municipalities within their local permitting systems and processes. Building permit applications often require validation of a contractors license and license status. This API is designed to assist in this process.

The current version and release for the API requires an API key associated to the municipal or vendor implementation.

Resources & Documentation

The API is documented at the following URLs:

  • Production: A public version of the API containing all resources tested and determined to be real-time ready.
  • Test: A semi-public version of the API to be used for testing vendor implementations and upcoming changes. This environment is not guaranteed to have up-to-date data and should only be used for testing purposes.

These two environments are both available for use by authorized municipalities and vendors.


The current release of the API requires an API key that is associated with a municipality or vendor. Your API key should be added to all API requests in the X-API-Key HTTP header.

Vendor and User Registration

Vendors and application developers can request an API key on the Request Access page.

Reporting Issues

To report issues with the API, please contact Susan.Noyes@mass.gov.