Software Package Data Exchange (SPDX) is a file format used to document information on the software licenses under which a given piece of computer software is distributed. SPDX is authored by the SPDX Working Group, which represents more than twenty different organizations, under the auspices of the Linux Foundation.
SPDX describes the exact terms under which a piece of software is licensed. It does not attempt to categorize licenses by type, for instance by describing licenses with similar terms to the BSD License as "BSD-like".
The current version of the standard is 2.2.
The current version of the standard is 2.2 and was ratified in May 2020.
The version 2.1 was ratified in November 2016.
Each license is identified by a full name, such as "Mozilla Public License 2.0" and a short identifier, here "MPL-2.0".
Licenses can be combined by operators
OR, and grouping
There is also a "+" operator, when applied to a license, means that future versions of the license apply as well. For example,
Apache-1.1+ means that
Apache-2.0 may apply (and future versions if any).
In 2020, the European Commission publishes its Joinup Licensing Assistant, which makes possible the selection and comparison of more than 50 licenses, with access to their SPDX identifier and full text.
The GNU family of licenses (e.g., GNU General Public License 2.0) have the choice of choosing a later version of the license built in. Sometimes, it was not clear, whether the SPDX expression
GPL-2.0 meant "exactly GPL version 2.0" or "GPL version 2.0 or any later version". Thus, since version 3.0 of the SPDX License List, the GNU family of licenses got new names.
GPL-2.0-only means "exactly version 2.0" and
GPL-2.0-or-later means "version 2.0 or any later version".