diff --git a/Gruntfile.js b/Gruntfile.js
index 70989c7..fd590ce 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -18,6 +18,10 @@ module.exports = function (grunt) {
         siteUrl: 'http://mydomain.net/',
         generateSitemap: true,
         generateRobotstxt: true,
+        tags: {
+          countargs: require('./test/tag'),
+          markdown: require('./node_modules/swig-extras/lib/tags/markdown')
+        },
         test: {
           var1: 'long path file',
           var2: 'short path file'
diff --git a/README.md b/README.md
index 607a4da..d2f88ef 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,9 @@ swig: {
     init: {
         autoescape: true
     },
+    tags: {
+        countargs: require('./test/tag')
+    },
     dest: "www/",
     src: ['**/*.swig'],
     generateSitemap: true,
@@ -70,6 +73,28 @@ You need to give the relative path to the output html file for this to work.
 Path and base name of the source template file are available in `tplFile` variable, `tplFile.path` for
 the path and `tplFile.basename` for the basename.
 
+The 'tags' property is an object that allows you to extend swig with any tag found on
+internet with the [common structure](https://github.com/paularmstrong/swig/blob/v1.3.2/lib/tags/block.js).  
+Key, value of the object is respectively: name of the tag, library/file required.
+Value it's always a `require()`, it may be a _custom_ file of yours or another NPM library.  
+[swig-extras](https://github.com/paularmstrong/swig-extras) and
+[swig-extensions](https://github.com/assemble/swig-extensions) tags are supported, you need to require
+directly the file, ex: `require('./node_modules/swig-extras/lib/tags/markdown')`
+
+Common structure:
+```javascript
+  exports.parse = function(str, line, parser, types, stack, options)
+  exports.compile = function(compiler, args, content, parents, options, blockName)
+  exports.ends = true/false
+  exports.block = true/false
+```
+Refer to [official Swig documentation](http://paularmstrong.github.io/swig/docs/extending/#tags).
+
+The 'filters' property allows you to expose custom filters to your templates.
+In the above example the filter `f` is created and mapped to the CommonJS file
+module named `myfilter.js` at the root of the project. The module must export a
+function whose name matches the filter ('f' in this case).
+
 ## Contributing
 In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using [Grunt](http://gruntjs.com/).
 
diff --git a/package.json b/package.json
index 66816bf..53b89c8 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,8 @@
     "grunt": "~0.4.1",
     "grunt-contrib-clean": "~0.5.0",
     "grunt-mocha-test": "~0.7.0",
-    "grunt-contrib-jshint": "~0.7.2"
+    "grunt-contrib-jshint": "~0.7.2",
+    "swig-extras": "0.0.1"
   },
   "peerDependencies": {
     "grunt": "~0.4.1"
diff --git a/tasks/swig.js b/tasks/swig.js
index bce763b..bf6ecfa 100644
--- a/tasks/swig.js
+++ b/tasks/swig.js
@@ -21,6 +21,20 @@ module.exports = function(grunt) {
       swig.setDefaults(config.data.init);
     }
 
+    if (config.data.tags !== undefined) {
+      Object.keys(config.data.tags).forEach(function (tag, index) {
+        var tagObj = config.data.tags[tag];
+        // compatibility with swig-extentions and swig-extras
+        var block = tagObj.blockLevel !== undefined ? tagObj.blockLevel : tagObj.block;
+        // ext is an extension to the interpreter, usually exposes functionality, ex: a markdown compiler
+        // as an object in the swig context (_ctx.<objectname>)
+        if (tagObj.ext) {
+          swig.setExtension(tagObj.ext.name, tagObj.ext.obj);
+        }
+        swig.setTag(tag, tagObj.parse, tagObj.compile, tagObj.ends, block);
+      });
+    }
+
     try {
       globalVars = grunt.util._.extend(config.data, grunt.file.readJSON(process.cwd() + '/global.json'));
     } catch (err) {
diff --git a/test/fixtures/markdown.swig b/test/fixtures/markdown.swig
new file mode 100644
index 0000000..f749035
--- /dev/null
+++ b/test/fixtures/markdown.swig
@@ -0,0 +1,29 @@
+{% markdown %}
+# swig extensions
+
+> Tags, filters, and extensions for [Swig](http://paularmstrong.github.io/swig/), the most awesome template engine for node.js.
+
+This project is based on (and complementary to) [swig-extras](https://github.com/paularmstrong/swig-extras), from [@paularmstrong](https://github.com/paularmstrong)
+
+
+## Getting started
+
+Use a filter:
+
+```
+var swig = require('swig');
+var extensions = require('swig-extensions');
+
+extensions.useFilter(swig, 'markdown');
+```
+
+Use a tag:
+
+```
+var swig = require('swig');
+var extensions = require('swig-extensions');
+var mySwig = new swig.Swig();
+
+extensions.useTag(mySwig, 'markdown');
+```
+{% endmarkdown %}
diff --git a/test/fixtures/tag.swig b/test/fixtures/tag.swig
new file mode 100644
index 0000000..d9146b5
--- /dev/null
+++ b/test/fixtures/tag.swig
@@ -0,0 +1,3 @@
+{% countargs 'firstarg' 'secondarg' %}
+  This part gets ignored in this test!
+{% endcountargs %}
diff --git a/test/swig_test.js b/test/swig_test.js
index 7f250e6..ccf78a7 100644
--- a/test/swig_test.js
+++ b/test/swig_test.js
@@ -1,3 +1,4 @@
+/* global describe:false, it:false */
 'use strict';
 
 var assert = require('assert'),
@@ -45,4 +46,12 @@ describe('grunt-swig', function() {
     helpers.assertFile('test/dest/robots.txt');
   });
 
+  it('should compile a custom tag', function () {
+    helpers.assertFile('test/dest/fixtures/tag.html', /args\:.*firstarg/);
+  });
+
+  it('should compile a custom tag from swig-extras', function () {
+    helpers.assertFile('test/dest/fixtures/markdown.html', /a href=.http\:\/\/paularmstrong/);
+  });
+
 });
diff --git a/test/tag.js b/test/tag.js
new file mode 100644
index 0000000..c16eb68
--- /dev/null
+++ b/test/tag.js
@@ -0,0 +1,27 @@
+// Official documentation about extending Swig Tags
+// http://paularmstrong.github.io/swig/docs/extending/#tags
+
+// Source code of how parse is defined:
+// https://github.com/paularmstrong/swig/blob/v1.3.2/lib/parser.js#L550-L570
+//
+// Correctly writing swig extensions might be tricky, get an idea about what
+// a TokenParser is: https://github.com/paularmstrong/swig/blob/v1.3.2/lib/parser.js#L109-L127
+exports.parse = function(str, line, parser, types, stack, options) {
+  parser.on(types.STRING, function (token) {
+    // strip quote or double quote, they _also_ get matched
+    token.match = token.match.replace(/^("|')|("|')$/g, '');
+    this.out.push(token.match);
+  });
+  return true;
+};
+
+// Source code, to see how it gets used:
+// https://github.com/paularmstrong/swig/blob/v1.3.2/lib/parser.js#L720-L738
+//
+exports.compile = function(compiler, args, content, parents, options, blockName) {
+  var concatArgs = '[ ' + args.join(', ') + ' ]';
+  return '_output += "args: ' + concatArgs + '";\n';
+};
+
+exports.ends = true;
+exports.block = true;