A little Javascript/SVG application to create dungeon maps for role-playing games.
Perl6 JavaScript Makefile
Latest commit fb96787 Feb 19, 2017 @kensanata Ignore the Firefox tests



Open the gridmapper.svg file using your browser and you have a very simple dungeon mapping tool.

  • quick keyboard navigation
  • support for multiple levels
  • collaboration with others

The user interface comes with a help screen explaining all the details, and a link to a demo. The map icons are inspired by the icons in Moldvay's Basic D&D. There's a screenshot in this review on RPG Geeks. Here's a Master Dungeon Mapping Key PDF, if you want something more recent.


Table of Contents

It's Free

Also note that Gridmapper is totally free and gratis. It costs nothing to use, and you can do with it what you want. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.

No Internet Explorer

Written using Vanilla JS. Unfortunately, Internet Explorer isn't well supported. That's because it mixes SVG and XHTML in the same document and that appears not to work for IE. I'm trying to simply remove the stuff that doesn't work.


You will have noticed that those example URLs contain a lot of gibberish past the questionmark. This is the URL's query string. It's a sort of code that's very close to a stream of keyboard commands. You can get this link by clicking on Prepare Link and then clicking on the resulting Link. Perfect for sharing and bookmarking.

For more examples, check out this Google+ Collection.

How to Collaborate

Gridmapper allows multiple people to draw on the same map. In order to do this, you must all type the same map name into the text area and click the Join link. You probably still need a way to talk or chat online.


Alternatively, one of you opens Gridmapper, provides a name in the text area and clicks Join. The others connect to the Gridmapper Server and click on the map, there.

If you want to keep it private, put a password on the second line.

How to Save

This being a very simple web application, it has no access to your file system. And worse: If you use "Save As..." in Firefox or Chrome you'll save a copy without any of the changes you made!

These are your options:

  1. If you're using Safari, you can just save the page. This will create a webarchive.

  2. Click on Text Export and copy the content of the text area into a text file. When you come back later, paste the text file into the text area and click Text Import. This text file is basically a little script recreating your dungeon. This does not work for Internet Explorer.

  3. Click on Link and bookmark the new page. The link now basically contains a little script recreating your dungeon. You might have to use a URL shortener such as goo.gl when pasting the URL into a chat window or when sharing it on social media. As browsers and web sites have size limitations on the length of a link, this will not work for big dungeons. This seems to be the only thing that works for Internet Explorer.

  4. Click on Download, right-click on the resulting SVG link and pick Save As.... This is also what you would use if you wanted to continue working on your dungeon using an SVG editor such as Inkscape. This will also allow you to save the map as a PDF file. This does not work for Internet Explorer.

  5. Click on Download and click on the resulting PNG link. This downloads or opens a bitmap image. This is what you would use if you wanted to continue working on your dungeon using Gimp or Photoshop. Remember, if you want to print the dungeon, you need 300 dpi or 300 pixels per inch. You're probably better off using the SVG file and converting it to PDF. This does not work for Internet Explorer.

  6. Click on Save to Wiki. This will make your wiki public, which is nice. It may also not be what you want if your players are watching the wiki. This does not work for Internet Explorer. In order for this to work, you need to provide some information in the text area: put the dungeon name on the first line, your name on the second line, and a description on the third line. Example:

Demo Dungeon
Alex Schroeder
This is the Demo Dungeon

If you choose to save your dungeon to the wiki, it will appear on the Gridmapper Campaign Wiki.

Upgrading your local copy of Gridmapper

Let's assume you downloaded a copy of Gridmapper and started creating your dungeon. Then you discovered that there's a new release out there. How can you upgrade your local file? Easy: use Text Export and Text Import.

  1. Open your local copy

  2. Click on Text Export

  3. Copy the text and save it somewhere

  4. Download a new copy of Gridmapper and open it

  5. Paste the text

  6. Click on Text Import

  7. Click on Prepare Download, click on the resulting Download link and save the file

Check that everything works before deleting your old copy. :)


It's possible to use the text area for some simple scripting. Paste the following in the text area, for example, and use Ctrl Enter as you move around on the map. It will surround your current square with walls.

[-1,-1]fff[-3,1]f f[-3,1]fff[-2,-1]

Scripting works by typing the commands you would need to type, with the following additions:

  1. f will place a floor and automatically advance (like a right arrow)

  2. - will move left by one (like a left arrow)

  3. . is used to stop rotations; thus ddd will place a door and rotate it three times where as d.dd will place one door and a second door, and rotate it once

  4. ; is used to pause for half a second; it might be useful if you're writing a demo for somebody else

  5. (x,y) will automatically move to the new position (be sure to add 0.5 to either x or y in Wall Mode); note that (0,0) is the top left corner and positive y is down

  6. [dx,dy] will move the current position relative to the current position; given that positive y is down, [0,1] is the equivalent of moving one down

Editing Maps using a Text Editor

Assume you have these two maps: One and Two. Use Text Export to get at their code.


 wft fw.wfwwfww.dddfw
 wfffwnnnn nn wfwwfwwfw
 ww ww w.dfffwfn nnn w
   ww ww ww wfnnnn fd
      ww ww ww


 ffnn n nn ffnn
 dfb fdfwfwfb f
 ffnnn fwfdffnnn

First, we need to shift it over by 10 spaces:

           ffnn n nn ffnn
           dfb fdfwfwfb f
           ffnnn fwfdffnnn

Then we combine them, and we add a little extra: we can tell Gridmapper to return to the top left corner by providing (0,0). Here's the combined map.

 wft fw.wfwwfww.dddfw
 wfffwnnnn nn wfwwfwwfw
 ww ww w.dfffwfn nnn w
   ww ww ww wfnnnn fd
      ww ww ww
           ffnn n nn ffnn
           dfb fdfwfwfb f
           ffnnn fwfdffnnn

Paste it into the text area and click Import Text. That's it. Result: Combined Map

How to extend Gridmapper

Let's assume you want to add wells as variants of statues to Gridmapper – and let's assume this had not yet been implemented. How would you do it?

Step 1: Find the SVG definition of a statue and add the SVG you want right next to it. Where to learn about SVG? Personally, I usually just look at these sources:

  1. The SVG Specification
  2. The SVG tutorials by Jakob Jenkov
  3. The SVG section on the Mozilla Developer Network

The outermost element needs to have an id attribute that you will be referring to later. It also needs a width attribute. This is used to scale your element.

Thus, here's a little SVG element containing the white floor rectangle and two circles. The outermost element has both an id and a width attribute.

<g id="well" width="100">
  <rect width="100" height="100" fill="white" stroke="black" stroke-width="10"/>
  <circle cx="50" cy="50" r="25" fill="black"/>
  <circle cx="50" cy="50" r="15" fill="black" stroke="white" stroke-width="10"/>

Step 2: Register the variants. What we need to do is tell Gridmapper that hitting v on a statue will turn it into a well and hitting v on a well will turn it into a statue. Find the variants in the source code and add the following:

variants: {
  'statue': 'well',
  'well': 'statue',

Step 3: Document it. Find the section at the end where all the tiles are documented. Search for #statue. Then, append something like the following:

<a xlink:href="javascript:interpret('bv')" title="well">
  <use x="40" y="1" xlink:href="#empty"/>
  <use x="40" y="1" xlink:href="#well"/>

Save it, test it, you're done!

Installation on your own Web Server

Since the query string is of utmost importance, the limitations on request length probably needs to raised. By default, Apache 2 has a limit of 8190 for these two options. I've increased them as follows in my web server config file:

LimitRequestLine      32000
LimitRequestFieldSize 32000

If you want hosting to work, you'll need to install gridmapper-server.pl as a Mojolicious app using Hypnotoad. You cannot use Toadfarm, because it's important that the server use only one instance. All the hosts and clients are in-memory. Nothing is saved to the disk. Remember to change the hostname and port at the top of the file.

If you're using Apache 2.2.22 (Debian Wheezy) as a proxy, you're in trouble. The gridmapper-server itself is using HTTP on port 8082 and the /join and /draw URLs are using WebSocket. This requires mod_proxy_wstunnel. This required recompiling a patched Apache and copying both mod_proxy and mod_proxy_wstunnel. You can find some links on my blog post.

Apache config:

ProxyPass /gridmapper-server/join ws://campaignwiki.org:8082/join
ProxyPass /gridmapper-server/draw ws://campaignwiki.org:8082/draw
ProxyPass /gridmapper-server  http://campaignwiki.org:8082/

Starting Hypnotoad:

hypnotoad gridmapper-server.pl

See Also

The project was the result of admiring Daniel R. Collins' original GridMapper 1.0.

This originally started as a Clojure project. You can find the Clojure code on the clojure branch.

There is also a branch called c2 which uses C2 to create a web application. Unfortunately, it doesn't scale well: when you use a 30×30 grid, it's too slow. I decided to move to VanillaJS.

There's also a very good looking, Flash based website with a similar interface called ANAmap.