Block ESP

A clean, instant Block ESP for Fabric — Minecraft 1.21.11

Overview

Block ESP is a lightweight, fully configurable Block ESP (Extra Sensory Perception) mod for Minecraft. It draws wireframe outlines around the blocks you choose — ores, chests, shulker boxes, spawners, vaults, suspicious sand, sculk, and any of the ~1200 blocks in the game — visible through walls.

Toggle it with a single key. No chunk reload. No freeze. No client/server lag. Just press X and every block you've selected lights up instantly.

Why this ESP and not another?

• Instant toggle — no chunk re-mesh, no freeze, no waiting for chunks to reload. Press X, ESP is on. Press X again, it's off.
• Pick exactly what you see — a searchable grid of icons exposes the entire Block registry. Search by name in your game's language (English or French), tick what you want.
• Sensible defaults — by default the ESP enables ores (overworld + deepslate + nether), all 17 shulker box variants, chests / barrels / hoppers / dispensers, crafting utility blocks, redstone, spawners, trial spawners, vaults, infested blocks, suspicious sand/gravel, sculk, light sources, amethyst, player heads, end portal frames, dragon egg, beacon, conduit, respawn anchor — and more.
• Color-coded — every default block has a pre-assigned outline color (diamond = cyan, gold = yellow, emerald = green, redstone = red, chests = gold, spawners = light blue, etc.).
• ModMenu integration — a full in-game config screen with a search bar, render-distance slider, ESP ON/OFF toggle, scrollable grid of icons, and Reset / All ON / All OFF / Done buttons.
• Performance-first — the render loop uses a primitive long hashset (no autoboxing), pre-decoded color channels, and a throttled incremental chunk scanner. 100k+ highlighted blocks no longer tanks your FPS.
• Bilingual — English (en_us) and French (fr_fr).

Features

• Toggle with X — instant on/off, no chunk reload.
• Searchable grid of every block in the game (~1200 blocks).
• Render distance slider — 1 to 16 chunks around the player.
• Pre-assigned colors for the catalog blocks (ores, containers, spawners, etc.).
• Background scanner — daemon thread pool, never blocks the render thread.
• Chunks re-scan as the player moves (throttled, distance-sorted queue).
• Connected outlines — adjacent enabled blocks share edges (clean look, fewer vertices).
• HUD toast — a green "✓ ESP ON" or red "✗ ESP OFF" pill appears above the hotbar for ~3s after each toggle.
• ModMenu config screen — search bar + slider + grid + ON/OFF + Reset / All / Done.
• Client-side only — works on any vanilla server. The server doesn't see anything.

Installation

1. Install Fabric Loader 0.17.0 or newer for Minecraft 1.21.11.
2. Install Fabric API.
3. (Optional) Install ModMenu for the in-game config screen.
4. Drop blockesp-1.0.0.jar into your .minecraft/mods/ folder.
5. Launch Minecraft 1.21.11 with the Fabric profile.

Usage

Default highlighted blocks

• Ores — coal, iron, copper, gold, redstone, lapis, diamond, emerald (overworld + deepslate variants), nether quartz, nether gold, ancient debris, gilded blackstone.
• Storage / loot — chest, trapped chest, ender chest, barrel, hopper, dispenser, dropper, all 17 shulker box variants.
• Crafting / utility — crafting table, enchanting table, chiseled bookshelf, bookshelf, lectern, anvil (all states), smithing table, loom, cartography table, fletching table, grindstone, stonecutter, furnace, blast furnace, smoker, brewing stand, cauldron (all variants).
• Redstone — repeater, comparator, redstone lamp, wire, torch, lever, daylight detector, target, observer, piston, sticky piston, note block, jukebox.
• Spawners & special — spawner, trial spawner, vault, dragon egg, beacon, conduit, respawn anchor, end portal frame, end portal, end gateway.
• Dangerous / useful — TNT, obsidian, crying obsidian, reinforced deepslate.
• Infested blocks — all 7 silverfish variants.
• Archaeology — suspicious sand, suspicious gravel.
• Sculk — sculk, shrieker, catalyst, sensor, calibrated sensor, vein.
• Light sources — glowstone, sea lantern, shroomlight, end rod, lantern, soul lantern, torch, soul torch, glow lichen.
• Amethyst — budding, small / medium / large bud, cluster.
• Player heads & skulls — player, skeleton, wither skeleton, zombie, creeper, dragon, piglin (head + wall variants).
• Misc valuable — lightning rod, bell, sponge, wet sponge, cobweb.

Performance

Block ESP is built around a background scanner running on a daemon thread pool, completely decoupled from the render thread. The render loop only reads a pre-built list of targets and draws wireframe outlines — it never touches world data.

The hot path has been heavily optimized:

• Position lookups use a primitive LongOpenHashSet (fastutil) — no Long autoboxing on the contains() calls.
• Color channels (r, g, b, a) and the packed ARGB int are pre-decoded at scan time inside each EspTarget record — no per-frame bit-shifting.
• The render thread takes a single per-frame snapshot under a ReadWriteLock and uses it lock-free.
• The chunk scanner is throttled (max 8 chunks/tick) and sorted by Manhattan distance to the player — the chunks nearest to you light up first.
• Math.sqrt removed from the line rasterizer — cube edges are axis-aligned, the normal is already a unit vector.

Compatibility

• Minecraft 1.21.11 (only).
• Fabric Loader 0.17.0+.
• Fabric API (required).
• ModMenu 17.0.1 (optional, but strongly recommended — without it you can't open the config screen).
• Java 21+.
• Client-side only — safe on any vanilla server. Doesn't modify any server behavior.

Frequently Asked Questions

Q: Can I use this on a server? Yes. Block ESP is 100% client-side. The server doesn't even know you have it installed. Works on vanilla servers, Realms, and any modded server that allows client mods.

Q: Will this get me banned? It depends on the server's rules. Block ESP is a "client enhancement" that gives you an unfair advantage — most PvP servers and competitive servers ban it. Survival servers, private servers, and your own worlds are fine. Always check the server's rules before using it.

Q: Can I add my own blocks? Yes. Open ModMenu → Block ESP → Configure, and use the search bar to find any block in the game. Tick the ones you want. User-enabled blocks that aren't in the catalog use white outlines by default.

Q: How do I change the colors? Colors are currently defined in the source code (EspBlocks.java). Edit the catalog and rebuild to change the defaults. A config-screen color picker is planned for a future release.

Q: Why no chunk re-mesh like other ESP mods? Chunk re-meshing causes the freeze you see in older ESP mods. Block ESP draws the outlines as a separate overlay on top of the world, using a custom RenderType with NO_DEPTH_TEST — that's why the outlines are visible through walls and why the toggle is instant.

Credits & License

• Author — LunoX
• License — MIT (free to use, modify, redistribute with attribution)

If you like the mod, please leave a comment / favorite  on the project page — it really helps with visibility. Thanks!