VeinSim

VeinSim predicts ores, structures and biomes from your world's seed and draws them as colored, see-through wireframe boxes — so you can find real veins and real structures even on servers running anti-xray.

Instead of reading hidden block data (like an X-ray mod), VeinSim re-simulates Minecraft's world generation from the seed.

And if you don't know the seed, it can work it out for you — just by walking past structures.

Features

Seed cracking

• Automatic — recognises structures as they come into view and cracks the world seed on its own. No commands, no setup; just explore.
• Works from landmarks — shipwrecks, desert pyramids, igloos, jungle temples, swamp huts, ocean ruins, and pillager outposts.
• Per-server memory — a cracked seed is saved against that server and reused next time you join.

Ore prediction

• Seed-based — calculates ore positions by replicating vanilla world generation. Not block-reading; anti-xray proof.
• See-through wireframe boxes — every predicted ore outlined in a bright, color-coded box visible through terrain.
• All ores — overworld, deepslate variants (toggled separately), and Nether ores.
• Adjustable search range — 1 to 16 chunks around you.
• Result limit — cap how many boxes show at once (nearest first) to keep performance smooth.
• Nearest-vein-only mode — show just the closest vein of each selected ore for quick runs.

Structures

• 22 structure types located from the seed — villages, outposts, pyramids, temples, igloos, huts, mansions, trail ruins, monuments, ocean ruins, shipwrecks, buried treasure, ruined portals, strongholds, mineshafts, ancient cities, trial chambers, fortresses, bastions, nether fossils and end cities.
• See-through boxes drawn around located structures.
• Search radius up to 256 chunks.

Biomes

• Find any biome from the seed, out to 25,600 blocks.

Compass binding

• Bind your compass to a structure or biome and it points there — including a distinct model when you arrive.

Quality of life

• In-game config menu — toggle everything without leaving the game.
• Hold or Toggle activation for the ore overlay.
• Chat status messages — Enabled/Disabled notices (can be turned off).
• Persistent settings — everything saves to config/vein-sim.json.

Quick Start

1. Install Fabric Loader + Fabric API, then drop VeinSim in your mods folder.
2. Join your world or server.
3. If you know the seed: /VeinSim seed 123456789 If you don't: just play. Walk past a few structures and VeinSim cracks it for you, then tells you in chat.
4. Press V to open the config menu and choose what to find.
5. Hold (or toggle) X to display the ore boxes. Go mine.

Hotkeys & Commands

Activation can be set to Hold (active only while held) or Toggle in the config menu.

Config Menu

Open with V.

• Activation Key — rebind the overlay key.
• Mode — TOGGLE or HOLD.
• Search Range — 1–16 chunks. Larger ranges fill in over a second or two.
• Max Boxes — cap the boxes rendered (nearest first).
• Nearest vein only — only the closest vein of each enabled ore.
• Chat status — Enabled/Disabled messages on or off.
• Auto-crack — let VeinSim find the seed on its own (on by default).
• Structure boxes — draw boxes around located structures.
• Structure / biome search radius — up to 256 chunks and 25,600 blocks.
• Ore toggles — each ore individually:
  • Overworld: Coal, Iron, Copper, Gold, Lapis, Redstone, Diamond, Emerald
  • Deepslate: every deepslate variant, toggled separately
  • Nether: Ancient Debris, Nether Quartz, Nether Gold

Heavy settings show an in-menu warning so you know what may cause lag.

Accuracy

Ores

VeinSim reproduces Minecraft's generation algorithm block-for-block. Ores fall into two groups:

• Exact — iron, copper, redstone, lapis, gold, emerald, coal (upper), nether quartz, nether gold, ancient debris, and buried diamond/lapis. Fully deterministic and predicted precisely.
• Approximate — coal (lower) and regular diamond. Their generation depends on nearby cave air, which cannot be derived from the seed alone by any tool. The closest veins still show, but expect some extras.

Tip: enable Nearest vein only with a small Search Range for the cleanest results while mining.

Structure recognition

Measured over 50 real structures: 46 found. Desert pyramids, igloos, jungle temples, shipwrecks, swamp huts and pillager outposts were recognised every single time.

Ocean ruins are the exception, and it's worth knowing why. Minecraft deliberately erodes them as it builds — often deleting around half the blocks — so a badly rotted ruin no longer resembles its own template closely enough to identify with confidence. Intact ruins are found; heavily eroded ones are not. This is the game's own randomness, not a bug, and no seed-based tool can recover what was never placed.

Missing one structure costs you nothing: cracking simply uses the next one you walk past.

Requirements

• Fabric Loader
• Fabric API
• Java 25
• Client-side only — does not need to be on the server.

Supported version:

Builds for 26.1.x and 1.21.11 are not yet available for this release.

Notes

• Seed cracking needs structures, so it works best while exploring new terrain.
• Everything is client-side: nothing is sent to the server, and no server-side permissions are required.