WorldJava
/seed
Prints the numeric seed of the current world to chat. Use it to reproduce the same terrain in another world or to plug into seed-map tools and finders.
Syntax
Examples
Show the current world's seed.
Permission level
/seed requires Cheats (op level 2). In single-player you need the world's "Allow Cheats" toggle on. On a multiplayer server you need to be opped — see /op.