Licensing
The Firebird database engine and its modules are released under an open-source license, the Initial Developer's Public License (IDPL), a variant of the Mozilla Public License (MPL). It does not require the developer to open the products using Firebird or even custom-derivatives made from its source code, but if the developer chooses to do so, then some terms and conditions should be honored. The IDPL allows the developer to make proprietary, closed-source applications that use Firebird or are based on it.
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