Google created the Structured Data Testing Tool (SDTT) which can help you develop, and test your structured markup.
You can load markup into the tool either directly or by supplying a URL. The editing environment for the tool provides these utilities to simplify markup testing:
- Automatic highlighting —once you load your content in the editor, you can click on a validated field on the right of the editor to see which line in your markup produced that field. This is handy for isolating syntax errors.
- Keyword completion of schema.org and JSON-LD keywords.
With Google Structured Data v3 you can directly type in the URL of the part of your page that you'd like to test from within the Dashboard.