Wiki for the global player leveling plugin
AuroraLevels is a Minecraft plugin developed for PaperMC (and its forks like Purpur and Pufferfish) and Folia. You can check out the source code on GitHub and download it for free on Modrinth. On the official Website you can download dev builds.
AuroraLevels provides a level for every player and doesn't take a position on how you award XP to your players to level up. You can define your leveling XP curve with a simple math formula. The plugin will award rewards (configured by you) to players as they level up. To some degree, for certain reward types (like permissions or stats from other plugins) it can also automatically correct the rewards for players if you change your config later on (eg.: you get the new permissions which wasn't in the config before or your bonus stats like health/strength from other plugins will recalculate).
You can define interval-based level matchers with priorities and custom rewards for certain levels. This means you can have different rewards for every 1, every 5, every 10, and every X level, depending on how you configure the plugin. You can also customize rewards for just specific levels, and these will become Milestone levels, where you reward your users with bigger bonuses, as server features unlock.
The plugin features fully customizable GUI menus for level progression and milestones.
All in all, this is a dead-simple, GUI-based, fully configurable, and customizable global player leveling plugin.