Valheim WebMap

Mod for your Valheim server. Makes a live map of your world you open in a browser. Share http://your_ip:3000. Players install nothing. Server only.

What it does

• Big map, every metre. One pixel is one metre. Seven zoom levels. Shows ground the way players shaped it: flat bases, moats, roads, farms. Trees, bushes and rocks drawn on top as their own layer. Checkbox turns them off. Cut a forest down, map shows the clearing next time it draws.
• Buildings. Every piece anyone placed, drawn as a footprint in its material colour. Hover to see what it is.
• 3D view. One click. Real ground, water, and every object drawn with the game's own model: walls, roofs, portals, ruins, trees, rocks, boats. Same spot, same rotation, same size as in the game. Ground has fine grain up close, no seams, no grid. Base looks like your base.
• Fog of war. Ground nobody walked on is black. No switch to turn it off. Close-up tiles only draw where players walked.
• Old trips count. Install the mod on a world you played for months and the map still opens up everywhere anyone has been. The world save remembers which zones the game built, and it only builds them where someone stood. The mod lifts the fog there at start. Your in-game map itself lives in your character file, which the server never sees, so this is the closest thing to it. See reveal_visited.
• Live players. Arrow points where they look. Health bar. Biome. PvP, sleeping, dead. Follow one. Pings and chat pins land on the map.
• Player card. Click a player, on the map, in 3D, or in the list. Card shows health, stamina, eitr, what they wear and hold, how long they played, deaths, distance walked, visits. Updates live. Buttons: follow, go to, switch view.
• Markers. Portals with their tags and links, tombstones, player bases, boats, carts, your own markers.json. Boss altars, dungeons, traders and the world seed are never sent out. No spoilers.
• Stats. Per player: time played, visits, deaths, distance, portal trips, biomes. Per server: day, explored %, pieces built, trees, who was online last 24 h.
• Events. Joins, leaves, deaths, chat, pings. Saved to events.jsonl.
• Export. Pick an area, get a 3D file. Ground, water, every building and object, trees, markers. Opens in Blender, Unreal, Unity, Godot. Unreal pack has a heightmap too. See docs/EXPORT.md.
• Also: share links, search, works on phone, dark UI, Discord webhook, POST /announce to shout at everyone.

Install

1. Put BepInEx on the server. Unzip. Copy the plugins/WebMap folder to

   <server>/BepInEx/plugins/WebMap
   

   Folder holds WebMap.dll, websocket-sharp.dll, web/. Mod managers (r2modman, Gale, Thunderstore) do this for you. Lost the web/ folder? No matter: a copy lives inside the DLL and the map still shows. Put a web/ folder next to the DLL and it wins, so you can change the page.

   Docker (lloesche/valheim-server): with BEPINEX=true, BepInEx lives at /opt/valheim/bepinex/BepInEx on the data volume. /config/bepinex is only config. Plugin goes to /opt/valheim/bepinex/BepInEx/plugins/WebMap. Easiest: bind-mount a host folder there. Example in tools/docker-compose.test.yml. Config lands in <config volume>/bepinex/com.valheimwebmap.server.cfg. Open the port: -p 3000:3000/tcp.

2. Start server once. It writes the default config to BepInEx/config.

3. Edit config if you want. Restart. Config is read at start only.

4. Open port 3000. Visit http://your_ip:3000.

Map data lives in plugins/WebMap/map_data/<World>/. Model library in plugins/WebMap/map_data/models/. Keep both when you update.

Behind Cloudflare or another cache? Purge it after every update, or set a rule to not cache this host. The mod already sends the right headers.

First start

Server draws the zoomed-out map first (zoom 0–5, ~500 tiles, one to two minutes on one core). Then close-up tiles where players walked. Page works right away: missing tiles show the zoomed-out one blown up, swap in when done. Counter bottom-left: drawn / waiting.

First start also exports the 3D models. A couple of thousand prefabs, a few minutes. Done once, kept forever. Log: WebMap: models exported N (readable meshes R, ...).

Textures

Server does not let anyone read textures. So the mod reads them straight out of the game's own files instead. Background thread, low priority, starts a few seconds after the first model export. Windows, Linux, Docker. Nothing to install. One to two minutes over ~2 GB of game files, once per game version. Log:

WebMap: extracting 142 textures from the game files in .../valheim_server_Data
WebMap: 139 of 142 textures extracted from 61 files in 74s, 3 not found
WebMap: 180 models to re-export with newly extracted textures

Textures are game files. Not in this repo. Not in the mod zip. Never shared. They only ever sit in your map_data/models/ folder, made from your own server. use_textures = false skips all of it (flat colours). texture_max_size caps them (default 512).

Doing it by hand, same job, plain Python 3, no packages:

python3 tools/extract_textures.py <valheim_server_Data> <plugins>/WebMap/map_data/models

Meshes

Same story for the shapes. The engine locks most meshes (about seven in eight: carts, beehives, ruins, rocks, furniture...). Ask it for the vertices and it says no. Old versions drew those as boxes, or left parts out: a cart with boxes but no cart. Now the mod reads the locked meshes out of the game files too, right after the textures, and draws the real thing. Once per game version, a few minutes. Log:

WebMap: extracting 1900 meshes from the game files in .../valheim_server_Data
WebMap: 1880 of 1900 meshes extracted from 800 files in 180s, 20 not found
WebMap: 1700 models to re-export with newly extracted meshes

Mesh files live in map_data/models/meshes/. Game data, same rules as textures: never in the repo, never in the zip, never served. Only the finished .glb models go to the browser. extract_meshes = false turns it off (locked meshes stay boxes). By hand:

python3 tools/extract_meshes.py <valheim_server_Data> <plugins>/WebMap/map_data/models
python3 tools/extract_meshes.py <valheim_server_Data> --dump Cart,beehive   # look inside the game files

Still a box or a gap? The log names every mesh it could not find or decode. Send it in an issue.

Server load

Map drawing runs on its own thread (render_threads, default 1, low priority). Game thread only does: one slow walk over the world every sweep_interval seconds (3,000 objects per frame), player snapshot once a second, fog, model export within export_ms_per_frame. PNGs are made by the mod's own writer, off the game thread.

If the engine refuses to sample ground off the game thread, the mod does a few rows per frame on it instead. Slower. Never freezes. render_threads = 0 forces that.

Disk: whole world at 1 m/px is ~6,400 tiles, few hundred MB. Only walked ground draws close up, so a normal world is tens of MB. max_render_zoom = 6 cuts that by four.

Config

Section	Key	Default	What
Render	render_threads	1	threads drawing tiles (0 = do it on game thread, slowly)
Render	prerender_zoom	5	draw the whole world up to this zoom at first start
Render	max_render_zoom	7	closest zoom over walked ground (7 = 1 m/px)
Render	height_max_zoom	7	closest zoom for height tiles (3D)
Sweep	sweep_interval	120	seconds between world walks
Sweep	zdos_per_frame	3000	objects looked at per frame during a walk
Markers	reveal_all	false	no fog: whole world shown and sent out. Testing only
User	always_map	true	lift fog where hidden players walk. Their spot stays hidden
User	always_visible	false	ignore players' "hidden" setting
User	show_last_seen_position	false	offline players' last spot in stats
Server	server_port	3000	HTTP port
Server	map_title	(server name)	title on the page
Server	enable_3d	true	offer the 3D view
Server	event_log	true	write events to events.jsonl
Server	legacy_map	true	build one big map.png for /map
Models	export_models	true	export prefab meshes for 3D
Models	object_categories	piece,other,rock,bush,tree	what the 3D view and export get
Models	use_textures	true	textures on 3D models (off: flat colours)
Models	texture_max_size	512	longest texture edge
Models	export_ms_per_frame	6	game-thread ms per frame for export
Texture	explore_radius	100	metres revealed around a player
Texture	reveal_visited	true	lift fog everywhere the world save shows players have been, even before the mod
Texture	reveal_visited_margin	3	how far in from the edge of the built zones the reveal stops (0 = 320 m, 3 = 150 m, 4 = 100 m)
Discord	discord_webhook, discord_invite_url		webhook for events
Server	webmap_url, max_pins_per_user		link shown in game, pin limit
User	web_pins	true	let the web page place pins (right click / long press)
Models	extract_meshes	true	read locked meshes out of the game files (else boxes)
Server	websocket_compression	false	permessage-deflate on the live feed. Off: IIS ARR and some proxies drop every frame with it on

Your own markers

Put markers.json next to the world's map data (plugins/WebMap/map_data/<world>/markers.json). Read again when it changes.

{ "sets": [
  { "id": "mines", "label": "Mines", "markers": [
    { "x": 2210, "z": 980, "label": "Silver mine", "icon": "mine", "description": "north face" }
  ] }
] }

Icons: pin dot fire mine house cave boss trader dungeon camp village ruin runestone wreck portal tombstone boat cart poi spawn.

Player card

Click a player. Card pops up next to them. Health, stamina, eitr as bars. State: PvP, sleeping, dead. Biome and coordinates. What they hold in each hand and wear on head, chest, legs, back, belt. Lifetime numbers: played, deaths, walked, visits, portal trips. Follow, go to, switch 2D/3D. Card stays open and updates live. Escape or click away closes it. Works on the 2D map, in 3D, and from the Players list. Game only sends current stamina and eitr, not the max, so those bars fill against 100 or the current value.

Export a 3D scene

Download button, top bar. Pick the area (what you see on the 2D map, or 256 m to 1.5 km around the centre), ground detail, what to include, format:

• glTF, instanced. One mesh per prefab, placed many times. Small file. Blender, Godot, three.js.
• glTF, one object per node. Unreal, Unity, anything that lacks the instancing extension. Bigger file, same stuff.
• Unreal pack. Zip: the flat scene, heightmap_r16.png for a Landscape, instances.csv and markers.csv in Unreal units, an editor Python script, README with the exact Landscape scale and location numbers.

Made in the browser from what the map already shows. Fog applies: nothing undiscovered leaves the server. Meshes and textures are the game's own files from your server. Use the export yourself, do not pass it around. Steps per editor in docs/EXPORT.md.

HTTP API

Path	Returns
/tiles/map/{z}/{x}/{y}.png	ground tile, zoom 0–7. 404 + X-WebMap-Tile: pending while drawing
/tiles/veg/{z}/{x}/{y}.png	tree and rock overlay, zoom 5–7, transparent PNG
/tiles/height/{z}/{x}/{y}.png	height tile, Terrarium encoding
/data/structures/index.json, /data/structures/{cx}_{cz}.json	pieces per 256 m chunk
/data/veg/{cx}_{cz}.bin	vegetation points per chunk (Vegetation.cs)
/data/objects/index.json, /data/objects/{cx}_{cz}.bin	every placed object per chunk: prefab, position, rotation, scale (WorldObjects.cs)
/data/prefabs.json	model library: which prefabs have a model, bounds, triangles, textures
/models/{hash}.glb, /models/tex_*.png	exported models and textures. Cacheable
/data/markers.json	marker sets
/data/players.json	live players: position, health, stamina, eitr, gear, state
/data/stats.json, /data/events.json, /data/pins.json	stats, events, pins
/data/fog.png	explored mask, north up
/config, /api/status	config, drawing and sweep status
POST /api/sweep	walk the world now
POST /api/rerender?zoom=N	redraw tiles from zoom N up (token)
POST /api/reexport	export every model again (token)
POST /api/reload	forget cached web files, refresh every open browser (token). Swap files in web/ without restarting the game
POST /announce	message on every player's screen (token)
/map, /map.jpg, /fog, /players, /pins, /messages, /structures, /structures/stats, /structures/refresh, /forest, /forest/stats, /vehicles	simple endpoints: one-image map, plain lists

Websocket at /ws. JSON frames: hello, players, events, tiles, world, ping, pin, rmpin, reload.

Tile grid: world is a 20,480 m square around the origin. Zoom 7: one pixel is one metre. Tile (0,0) is the north-west corner. Zoom z has 2^(7-z) metres per pixel. tx = floor((x + 10240) / (256 · 2^(7-z))), ty = floor((10240 − z_world) / (256 · 2^(7-z))).

Token

POST /announce, /api/rerender, /api/reexport, /api/reload need a secret in header X-Announce-Token. Secret is read from file announce.token next to the DLL. No file, no access.

New web files, no restart

Changed something in web/? Copy the files over, then:

curl -X POST -H "X-Announce-Token: yoursecret" http://localhost:3000/api/reload

Server forgets its cached copies and every open browser reloads. Only the web files. A new DLL still needs a game restart. For dev work set cache_server_files = false and the server reads from disk every time.

Pins

From the web page. Right click the map (long press on a phone). Pick a type, write a label, add pin. Your own pins have a "Remove pin" button. Only the browser that made a pin can remove it. web_pins = false turns this off. max_pins_per_user caps pins per browser, old ones go first.

From chat. Type in game:

• !pin [type] [text] — types dot, fire, mine, house, cave
• !undoPin, !deletePin [text]

Chat pins have a catch. Since Valheim 1.0 the game sends chat straight from player to player, not to the server. The server only sees chat while it passes it on between two or more players. Alone on the server, your !pin never arrives. Not a bug in the mod, nothing the mod can do. Use the web page, it always works. Pings (middle click on the in-game map) still reach the server, alone or not.

Build

Windows: .\build.ps1. Needs .NET SDK and the Steam "Valheim Dedicated Server" tool, or -ValheimManaged <path>. Linux/macOS: ./build.sh. Output: dist/ValheimWebMap-<version>.zip and dist/pkg/plugins/WebMap/. -Deploy <plugins dir> or --deploy copies the plugin there.

Public demo site

Want a demo people can click on without showing your real world? Run the mock server in Docker. Made-up island, fake players walking in circles, fake chat. No game files inside, nothing to leak, nothing it can write.

docker compose -f tools/docker-compose.demo.yml up -d --build

Port 3000. Put your reverse proxy or Cloudflare Tunnel in front on a demo hostname. Title and world name come from WEBMAP_TITLE and WEBMAP_WORLD in the compose file. Image is ~60 MB, uses under 100 MB RAM. Tiles are drawn on first request and cached; the demo loops forever.

Your real map: keep it for your players. Cloudflare Access, a password on the proxy, or a hostname nobody guesses. The mod itself has no login.

Try it without a real server

tools/mockserver.js (Node, no packages): serves the web app with a made-up world, fake players, fake events. node tools/mockserver.js, open http://localhost:3000.

tools/docker-compose.test.yml: real dedicated server (lloesche image) with a copy of your world.

# copy world folder to valheim-test\config\worlds_local\<World>\
.\build.ps1 -Deploy valheim-test\plugins
docker compose -f tools\docker-compose.test.yml up      # first run downloads server

Then http://localhost:3000. In game: Join by IP, 127.0.0.1:2456

A copied world lifts the fog where players have been (reveal_visited), not what each player's in-game map shows: that lives in their character file. Want it all: set reveal_all = true in valheim-test\config\bepinex\com.valheimwebmap.server.cfg and restart. Tiles still draw as you look.

Licence

MIT. See LICENSE. Leaflet (BSD-2) and three.js (MIT) vendored under web/vendor.