DB2 Express-C is the same database as IBM's commercial offerings but the company places limits on what kind of hardware it can run on.
It can be deployed on systems with two processor cores or up to two dual-core chips on Advanced Micro Devices- or Intel-based servers. The memory limit is 4GB but there are no limits on the size of database or number of users.
IBM's decision to add a free database to its lineup follows moves by its largest rivals in the database business, Oracle and Microsoft.
With the release of SQL Server 2005 late last year, Microsoft introduced a free version. Similarly, Oracle has a free product called Oracle 10g Express Edition.
The three corporate-database providers are all seeking to appeal to software developers, who help influence companies' technology decisions. In addition, open-source databases, which generally include a free edition, have risen in popularity in the past year.
Developer research firm Evans Data found that more than 70 percent of developers had installed and used an open-source database last year. Of the open-source databases, MySQL was by far the most popular among respondents, according to Evans Data.
IBM said that a future version of DB2 Express-C, code-named Viper, will include hybrid relational and XML database features. Viper is due for release this year.
