SDTT is a tool from Google which began life as the [Rich Snippets Testing Tool](https://developers.google.com/search/blog/2010/09/rich-snippets-testing-tool-improvements)back in 2010. Last year Google[announced plans](https://developers.google.com/search/blog/2020/07/rich-results-test-out-of-beta)to migrate from SDTT to successor tooling, the[Rich Results Test](https://search.google.com/test/rich-results), alongside plans to "deprecate the Structured Data Testing Tool". The newer Google tooling is focused on helping publishers who are targeting specific schema.org-powered[searc](https://developers.google.com/search/docs/guides/search-gallery)[h features](https://www.blogger.com/)offered by Google, and for these purposes is a huge improvement as it contextualizes many warnings and errors to a specific target application.