Is there a tool to view Terraria seeds?

Yes. Terraria includes a built-in World Seed feature that lets you view and copy the seed of any world from the world selection menu. You can reveal the seed in the world screen and use the Copy Seed button; since patch 1.4.0.1 seeds can be viewed, copied, and entered for worlds generated after that update (older worlds may not store seeds in the same way) World Seed. For the most part, this is the authoritative way to see a world’s seed directly in-game.

If you want to visualize a world map beyond what the in-game seed display offers, you’ll typically use third-party tools that read a saved world file rather than generate a map from a seed alone. Useful options include: - TerraMap (TerraMap Web/Windows) which loads your .wld world file in a browser or app to show a full map, biomes, spawn points, and dungeon locations; it is client-side and does not upload your data. - TEdit — Terraria Map Editor for editing maps and viewing/crafting in a standalone editor. - Terrafirma/other map viewers that can load a world file to display the complete map, chests, and features. Note that, in general, seed-only online viewers are not standard; most map previews require the actual world file rather than just the seed (a common topic in community discussions). See Reddit discussions for examples of the seed-map limitation.

In short: you can view seeds in-game via World Seed, and if you want a full-map view you’ll typically load your world file into a tool like TerraMap, TEdit, or Terrafirma.