Amazon DynamoDB local adds support for empty values for non-key String and Binary attributes and 25-item transactions
Amazon DynamoDB local, the downloadable version of DynamoDB, now supports empty values for non-key String and Binary attributes in DynamoDB tables. In addition, DynamoDB local has added support for up to 25 unique items and 4 MB of data per transactional request. With DynamoDB local, you can develop and test applications quickly in your local development environment without incurring any additional costs.
Source:: Amazon AWS