Source-Available Software
Source-available software refers to software distributed with its source code made available for users to view. However, unlike free software or open-source software, not all source-available software grants users the rights to freely use, modify, or distribute the code. It serves as an intermediary category between proprietary software and the open software movement, offering some transparency but not necessarily the freedoms associated with open-source software.
Key Characteristics
The primary characteristic of source-available software is the accessibility of its source code. This means users can inspect the code for educational purposes, security auditing, or to understand how the software works. However, the licensing terms typically restrict users from making alterations, distributing modified versions, or even using the software commercially without explicit permission.
Licensing
There is a variety of licenses under which source-available software can be released. These licenses usually define the boundaries of what users can and cannot do with the software. One notable licensing scheme is the Shared Source Initiative by Microsoft, which offers diverse source code access levels under different licenses.
Comparison with Other Software Models
While source-available software shares some common ground with free and open-source software, there are critical differences:
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Free and Open-Source Software (FOSS): FOSS is always source-available, but it also grants users the rights to use, modify, and distribute the software. Organizations like the Free Software Foundation and the Open Source Initiative maintain strict definitions of open-source software and its liberties.
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Proprietary Software: Proprietary software usually conceals its source code, preventing users from accessing or modifying it. However, proprietary software can be source-available if the vendor chooses to distribute the source code without permitting modifications. An example is certain projects under Microsoft's Shared Source Initiative.
Examples and Applications
Some software vendors provide source-available versions of their products for transparency or auditing purposes. These versions might be released to inspire trust in the software, demonstrate compliance with regulations, or facilitate integration with other systems by allowing developers to understand how the software operates in detail.
Terraform is an example of software that transitioned through these categories. Initially available as open-source under the Mozilla Public License, it adapted its licensing terms to restrict competitive use, illustrating the spectrum between open-source and proprietary models.