ToolAssist is a fully customizable, lightweight vein-mining plugin for Bukkit/Spigot/Paper 1.18 servers.

I've noticed that the only good vein mining resources on here are old and a lot of them are out of date.

This plugin is not only lightweight and fully customizable but will also run without issue on future versions of Minecraft without the need to update.

You can choose to use the configuration to define what blocks are targeted for each tool type, or to use an internally predefined set of blocks.
You can choose how large of a radius you'd like the plugin to search.
You can choose whether to have the vein mining active all the time, or to be activated by sneak (I'd not recommend changing this, it can get very annoying).
You can choose the default permission users are required to have in order to use the vein mining feature.

I'm constantly looking for feedback and suggestions on things to include in my plugins; give me a message, a reply, or open a ticket on the GitHub project if you think of something you'd like to see implemented.