by Flared - Lens Flare in Scripts and Addons

Flared is a real-time lens flare generator that works directly in the viewport of Blender, using Eevee engine. Now with full Cycles support!

So you can have a direct preview of the final result without the need to use the compositor. It's not screen space-based, so it works also when light sources move out of the screen.
It takes advantage of procedural materials, so it's resolution-independent. It's easy to use and customize and can help you to add cinematic looks to your 3D scenes or give more drama to your real video footages.
Flared it's not a physical simulation of the light path through the lens, it's a powerful artistic instrument.

Here is an example: in this short CGI video the Sun is made with Flared:

Here is another example of how it works:

Here is a generic video that shows some features of Flared (as it's an old video, maybe it's talking about old blender versions, don't care about it).

Flared has been on sale for 12 months. During this period, we had time to test and improve it. Here is the full Youtube Playlist with information and tutorials (note: some videos are obsolete, we have removed the anti-piracy system, so now you can work with Flared without any restrictions).

You can find more details on the official website too.