Older versions of Trapcode Particular (v2 and v3) had a "Demo Mode" that ran without a license but rendered with a red "X" or watermark. They simply stop working. Do not bother finding old installers; they won't work with modern After Effects (CC 2024/2025).
This is the forgotten gem. Go to Effect > Simulation > CC Particle World . Trapcode Particular Free Download After Effect
If you type this keyword into Google, YouTube, or torrent sites, you will find thousands of links. They promise a "direct download," "cracked license," "keygen," or "patch." Older versions of Trapcode Particular (v2 and v3)
Would you like tutorials for the built-in After Effects particle effects instead? or torrent sites
For abstract particle grids (like a flying logo breaking into dots), CC Ball Action is incredible.