LumiBrush brings light painting into Blender. Drag the brush across objects in your scene and real light appears exactly where you stroke, carrying true shadows, falloff and bounce. Egret Studios LLC describes it as a no-fakery light brush that keeps full control on every stroke after the fact.
The add-on works live in both Cycles and EEVEE, so the light you paint renders through Blender's own engines. It's a Blender extension compatible add-on covering versions 4.2 through 5.2, released under the GPL license.
Documentation is included, and Egret Studios LLC provides support along with product updates; the support period can be extended beyond the term bundled with the add-on. A demo video is available for a closer look, and the add-on is listed here as free.