Are Microsoft SQL Server "Express" editions free to develop on?

sql-server, sql-server-express

Solution

Yes, You can.

But Express version have few limitations

- SQL Server use only one CPU at a time

- Maximum memory is 1GB

- Database size limit is 4GB

And you can redistribute SQL Server, but you must register for that at Microsoft.

UPDATE - SQL Server 2008 R2

Database size limit is 10GB

Problem

Am I able to develop a software for free on Microsoft SQL Server 2005/2008 Express edition databases?

Original source