Valheim WebMap

A server-side mod that publishes a live web map of your Valheim world. Share http://your_ip:port and anyone can watch the map — clients do not need any mods installed.

This is a fork of h0tw1r3/valheim-webmap rebuilt for Valheim 1.0 (Deep North), with an overlay of player-built structures added.

For players to appear on the map they must set visible to other players on the in-game map screen (press m).

Dedicated server only.

Features

• An explorable map of your world in the browser — mousewheel zoom, pinch zoom on mobile.
• Shared fog of war: the map reveals only what players have actually explored.
• Connected players list, live positions, and auto-follow.
• In-game map pings show up on the web map.
• Player-built structures overlay — every placed piece is drawn in the colour of its material (wood, stone, black marble, thatch, metal, portals), so bases read as bases instead of blobs. Natural terrain and world-generated ruins are not drawn; the sweep keys off the piece's creator, so only things a player placed appear.
• Forest and logging overlay — standing trees shade the terrain, and felled ground stops being shaded, so clearings show through as bare terrain. Stumps are counted as the positive record of felling.
• Server announcements — POST /announce puts a message on every player's screen, for restart warnings and anything else worth saying in game.
• Connect / chat messages and Discord server-status notifications.

Installation

1. With BepInEx installed and working, place the WebMap directory in:

   Steam\steamapps\common\Valheim dedicated server\BepInEx\plugins\WebMap
   

2. Start the server once; a default config is written to:

   Steam\steamapps\common\Valheim dedicated server\BepInEx\config
   

3. Stop the server, edit the config, then start it again. BepInEx rewrites its config on shutdown, so changes made while the server is running are lost.

4. Open the configured port (default 8080) and visit http://your_ip:port.

HTTP endpoints

Besides the map UI, the server exposes:

Path	Returns
/map	the world render (PNG)
/map.jpg	the same render as JPEG — about a seventh the size, and the render is opaque so nothing is lost
/forest	forest cover and logging (PNG, transparent)
/forest/stats	tree and stump counts, and canopy density percentiles (JSON)
/vehicles	boats and carts in explored territory, with position and type (JSON)
/announce	POST a line to every player's screen (see below)
/fog	the explored mask (PNG)
/structures	player-built structures overlay (PNG, transparent)
/structures/stats	piece counts by prefab (JSON)
/structures/refresh	queue an immediate structure sweep
/players, /pins, /messages	live state (JSON)

The structure sweep walks every ZDO on the main thread in slices, so it runs on a slow cadence (2 minutes by default) rather than with the map refresh.

Updating

Clear your browser cache after updating, or hold shift and click reload.

Chat commands

Pins can be placed from in-game chat:

• !pin — a dot pin where you stand.
• !pin my pin name — a dot pin with a label.
• !pin [type] [text] — types are dot, fire, mine, house, cave.
• !undoPin — remove your most recent pin.
• !deletePin [text] — remove the most recent pin whose text matches exactly.

Commands are not case sensitive. Past the configured limit, a player's oldest pin is dropped.

Server announcements

POST /announce with the message as the body and an X-Announce-Token header shows the text on every connected player's screen. The shared secret goes in a file named announce.token beside the DLL — not in the BepInEx config, which is rewritten on shutdown and would discard it. With no token file the route is closed.

It deliberately uses MessageHud's ShowMessage RPC rather than chat: Chat gates every message on RelationsManager.CheckPermissionAsync(sender.UserId, …), and a server has no platform user id to satisfy that with, so chat sent from a server is dropped in silence.

How chat reaches the server on 1.0

Worth writing down, because it is not obvious. Valheim 1.0 sends player chat addressed to each permitted recipient, never broadcast:

Chat.SendText (shout)      -> InvokeRoutedRPC(user, "ChatMessage", headPoint, 2, userInfo, text)
Talker.Say   (normal/whisper) -> m_nview.InvokeRPC(user, "Say", (int)type, userInfo, text)

The server's RPC_RoutedRPC only calls HandleRoutedRPC when the target is itself or Everybody, so a hook there sees pings (which are broadcast) and nothing else. Player chat instead goes down the RouteRPC branch, which the server runs while forwarding the packet — so that is where this mod observes it. A shout arrives once per recipient and is de-duplicated on sender, method and payload within two seconds.

Upstream solved this by registering a fake server-side player so clients would address the server too. On 1.0 that patch stops anyone joining at all — the server stays healthy and registered but logs zero connection attempts — so it is not used here and the code is gone.

Local test server

./testserver.sh runs the same image the hosts do (indifferentbroccoli/valheim-server-docker) in podman, so a change can be tried against a real server before it goes anywhere near a live one.

./testserver.sh up       # first run downloads the game, ~10 min
./testserver.sh deploy   # build the mod, copy it in, restart
./testserver.sh status   # container + endpoints
./testserver.sh logs

Then join it in game with Join by IP -> 127.0.0.1:2456, password testpass123.

Two things it works around, both worth knowing:

• The image's install.scmd runs force_install_dir before login, and steamcmd then fails with Failed to install app '896660' (Missing configuration) having downloaded nothing. The script mounts a corrected copy with the order swapped. (The -beta argument is fine; it is only the ordering.)
• On an SELinux host the bind mounts need :z, or the container silently sees nothing.

Licence

MIT where applicable.

Credit

• 1.0 update and structures overlay by Hunter Boyd
• Maintained upstream by Jeff Clark
• Original work by Kyle Paulsen
• Background by webtreats, released under the CC BY 2.0 license.