The Explorer's Friend

A lightweight, fully server-side browser world map for Fabric servers.

Install one JAR on the server — players join with a completely vanilla client and open the live map in their browser. No client mod, no custom network protocol, nothing for players to install. (Putting the JAR into a client instance is harmless: singleplayer worlds get a map through the integrated server.)

Why another web map?

🎨 Mod blocks just work. On startup the mod inventories every installed mod JAR (SHA-256 content identity, nested jar-in-jar included), resolves each registered block through its blockstate → model → texture chain and computes a representative map color from the actual texture — in linear color space, alpha-aware, with outlier trimming. Everything is cached content-addressed: unchanged mods are never scanned twice, and a typical modpack re-scan after adding one mod takes milliseconds.

⚡ Minimal server impact. Nothing heavy ever runs on the server thread. Live world access is limited to hard-budgeted chunk snapshots (default ≤ 1.5 ms and ≤ 4 chunks per tick); full renders read region files from disk on worker threads without loading a single chunk. All queues are bounded with backpressure and job merging, and an MSPT-based auto-throttle pauses background rendering while the server is busy.

🗺️ Complete map features.

Topographic tiles with relief and water-depth shading, multiple zoom levels, incremental event-driven updates (block changes → debounced re-render)
Resumable, pausable full renders (/efmap render)
Claims overlay: auto-detected integrations for FTB Chunks and Open Parties and Claims (official APIs, nothing bundled) plus a JSON import bridge for other systems — semi-transparent fills, team colors, hover details
Live players with real skin heads (cached, privacy-hardened, vanish-API)
Markers via /efmap marker ... with a built-in icon library, plus banner markers: rename a banner in an anvil and place it — it appears on the map with its actual pattern; breaking it removes it
Layer panel in the web UI (claims / markers / banners / players), state persists in the browser

🔒 Safe and private by default. Binds to 127.0.0.1 until you decide otherwise (reverse-proxy guide included). Strict path validation, zip/PNG-bomb limits, bounded connections. Player layer: invisible/spectator filtering, position rounding and delay, name anonymization, per-player opt-out — or turn it off entirely.

📊 Observable. Structured console summaries, /api/v1/status JSON diagnostics and an optional Prometheus /metrics endpoint.

Quick start

Drop the JAR matching your Minecraft version (see the table below) + Fabric API into mods/.
Start the server → map at http://localhost:8080/.
Render the already-explored world: /efmap render minecraft:overworld

On dedicated servers the first start downloads the vanilla client JAR once from Mojang's official servers (block textures are not in the server JAR; SHA-1-verified, cached, can be disabled).

Minimum requirements

Seven release files cover every stable Minecraft version from 1.21.1 to 26.2 — install exactly the one matching your server (each file lists its supported game versions):

Minecraft	Java	Fabric Loader
1.21.1 – 1.21.8	21	≥ 0.16
1.21.9 – 1.21.10	21	≥ 0.17.0
1.21.11	21	≥ 0.17.3
26.1 – 26.2	25	≥ 0.19

Fabric API is required on every version.
Optional integrations: FTB Chunks, Open Parties and Claims (availability differs per Minecraft version — see the compatibility notes in the repository's docs/MULTIVERSION.md; the JSON claim import works everywhere)

The Explorer's Friend

Why another web map?

Quick start

Minimum requirements

Links