Six months ago Google deprecated the Structured Data Testing tool after they moved the main features to the Rich Results Test. However, it turns out the tool isn’t being completely shut down at all, it’s now being migrated to a new domain.
Site owners weren’t happy with the announcement about the loss of the Structured Data Testing Tool and Google have listened. This was a motivating factor behind this announcement. A refocused version of the tool is being migrated to Schema.org in April and it will no longer check for Google Rich Results Types.
The tool’s new purpose will be to check syntax and markup compliance alongside schema.org standards. Site owners will need to use existing tools, such as the Rich Results Test, to validate rich results markup. The relaunch of the Structured Data Testing Tool will happen in April.