- spark is released under the terms of the GNU GPLv3 license.
- spark-viewer is released under the terms of the GNU GPLv3 license.
- spark-docs is released under the terms of the CC-BY-SA-4.0 license.
spark has two profiler "engines":
asyncengine is a wrapper around async-profiler by apangin.
built-in javaengine is an improved version of the WarmRoast profiler by sk89q.
The spark-viewer user interface is based on the original WarmRoast UI, with a number of changes and improvements made over the years. The most significant of which was a re-write using the React framework, contributed by astei.