GNU General Public License v3.0
practical callout
If you modify GPL-3.0 software and distribute it, you must publish your modifications under GPL-3.0. Internal use and SaaS-style hosting (without distribution) do not require this. Use AGPL-3.0 instead if network deployment should trigger source-sharing.
what it permits
commercial usemodificationdistributionpatent grant
what it requires
disclose source codeinclude license and copyright noticestate changes to the codedistribute under the same license (copyleft)
network deployment note
Network deployment alone does not trigger GPL-3.0 distribution obligations. The copyleft triggers when you convey the software or a derivative to a third party.
tools using this license2 alternatives
sources