Merchant Markers Mod (1.19.3, 1.18.2) - Easily Recognize The Right Traders - 9Minecraft.Net
Flexible Marker - Tech Mod For Minecraft 1.15.2, 1.14.4 | PC Java Mods
GitHub - theAspenGrove/BlueMap-Signs: An add-on for the Minecraft mapping plugin BlueMap that aims to add ways for players to create markers by interacting with blocks in-game.
Forcing a Dynmap Marker update. | SpigotMC - High Performance Minecraft
GitHub - NerdNu/mapmarkers: A Python 3 script that reconciles `dynmap` markers with Minecraft map items.