SQL Server 2016 SP1 Express edition
Use SQL Server programming features to build small data-driven applications up to 10 GB of maximum disk size—that will scale across editions as you grow—with this free, entry-level database.
Why choose the Express edition?
Build web and mobile applications for multiple data types
Support structured and unstructured data while storing business data with native support for relational data, XML, and spatial data. Add geographical information to business applications and build location-aware applications. Increase granularity of temporal data with date and time data types.
Embed a lightweight database into basic desktop applications
Embed a SQL Server database into desktop applications or tools with SQL Server Express LocalDB—a lightweight deployment option for SQL Server Express with fewer prerequisites, running in-process with applications and not as a service.