Sleepycat License (sometimes referred to as Berkeley Database License or the Sleepycat Public License) is an OSI-approved open source license used by Oracle Corporation for the open-source editions of Berkeley DB, Berkeley DB Java Edition and Berkeley DB XML embedded database products older than version 6.0. (Starting with version 6.0 the open-source editions are instead licensed under the GNU AGPL v3.) The name of this license is derived from the name of the company which commercially sold the Berkeley DB products, Sleepycat Software, which was acquired by Oracle in 2006. Oracle continued to use the name "Sleepycat License" for Berkeley DB, despite not using the term "Sleepycat" in any other documentation until it changed to GNU AGPL with version 6.
The license is a strong form of copyleft because it mandates that redistributions in any form not only include the source code of Berkeley DB, but also "any accompanying software that uses the DB software". It is possible to circumvent this strict licensing policy through the purchase of a commercial software license from Oracle Corporation consisting of terms and conditions which are negotiated at the time of sale. This is an example of dual licensing.
The effect of the dual license creates financial exposure for commercial organizations, since there is considerable risk of becoming liable for payment of license fees to Oracle. Some people consider it to be a "sneaky" license. Mike Olson, co-founder and CEO of Sleepycat Software and Cloudera, said that "This is good business if you can get it, but your relationship with your customer begins based on a threat and that's not a really healthy place to start out."