diff --git a/README.md b/README.md
new file mode 100644
index 000000000..6835c8a7b
--- /dev/null
+++ b/README.md
@@ -0,0 +1,14 @@
+## Async Support
+
+harttle/shopify-liquid do NOT support async rendering, this is by design.
+
+The primary principle of harttle/shopify-liquid is EASY TO EXTEND.
+Async rendering introduces extra complexity in both implementation and extension.
+
+For template-driven projects, checkout these Liquid-like engines:
+
+* [liquid-node][liquid-node]: <https://github.com/sirlantis/liquid-node> 
+* [nunjucks][nunjucks]: <http://mozilla.github.io/nunjucks/>
+
+[nunjucks]: http://mozilla.github.io/nunjucks/
+[liquid-node]: https://github.com/sirlantis/liquid-node
diff --git a/context.js b/context.js
index fa57b44f3..7e9ff30fd 100644
--- a/context.js
+++ b/context.js
@@ -1,26 +1,33 @@
 const _ = require('lodash');
-const identifier = require('./identifier.js');
+const lexical = require('./lexical.js');
 
 var context = {
-    get: function(str){
-        if(identifier.isLiteral(str)){
-            return identifier.parseLiteral(str);
-        } 
-        if(identifier.isVariable(str)){
-            return _.get(this.context, str);
+    get: function(str) {
+        str = str && str.trim();
+        if(!str) return '';
+
+        if (lexical.isLiteral(str)) {
+            var a = lexical.parseLiteral(str);
+            return lexical.parseLiteral(str);
+        }
+        if (lexical.isVariable(str)) {
+            for (var i = this.context.length - 1; i >= 0; i--) {
+                var v = _.get(this.context[i], str);
+                if (v !== undefined) return v;
+            }
         }
         return '';
     },
-    init: function(ctx){
-        this.context = ctx;
+    push: function(ctx) {
+        return this.context.push(ctx);
     },
-    merge: function(ctx){
-        _.merge(this.context, ctx);
+    pop: function() {
+        return this.context.pop();
     }
 };
 
-exports.factory = function(_ctx){
+exports.factory = function(_ctx) {
     var ctx = Object.create(context);
-    ctx.init(_ctx);
+    ctx.context = [_ctx];
     return ctx;
 };
diff --git a/filter.js b/filter.js
new file mode 100644
index 000000000..595208bd0
--- /dev/null
+++ b/filter.js
@@ -0,0 +1,46 @@
+const lexical = require('./lexical.js');
+const _ = require('lodash');
+
+var filters = {};
+
+var _filterInstance = {
+    render: function(output, ctx) {
+        var args = this.args.map(arg => ctx.get(arg));
+        args.unshift(output);
+        return this.filter.apply(null, args);
+    }
+}
+
+function parse(str) {
+    var match = lexical.patterns.filterLine.exec(str.trim());
+    if (!match) {
+        throw new Error('illegal filter: ' + str);
+    }
+    var k = match[1],
+        v = match[2];
+
+    return factory(k, [v]);
+}
+
+function factory(name, args) {
+    var filter = filters[name];
+    if (typeof filter !== 'function') 
+        throw new Error(`filter ${name} not found`);
+
+    var instance = Object.create(_filterInstance);
+    instance.args = args;
+    instance.filter = filter;
+    return instance;
+}
+
+function register(name, filter) {
+    filters[name] = filter;
+}
+
+function clear() {
+    filters = {};
+}
+
+exports.parse = parse;
+exports.register = register;
+exports.clear = clear;
diff --git a/identifier.js b/identifier.js
deleted file mode 100644
index e9f61de37..000000000
--- a/identifier.js
+++ /dev/null
@@ -1,41 +0,0 @@
-const _ = require('lodash');
-
-var singleQuoted = /^'[^']*'$/;
-var doubleQuoted = /^"[^"]*"$/;
-
-var number = /^(?:\d+\.?\d*|\.?\d+)$/;
-var bool = /^(?:true|false)$/i;
-var range = /^\((\d+)\.\.(\d+)\)$/;
-
-var quoted = new RegExp(`${singleQuoted.source}|${doubleQuoted.source}`);
-var literal = new RegExp(`${quoted.source}|${range.source}|${bool.source}|${number.source}`, 'i');
-var variable = /^[a-zA-Z_]\w*(?:\.[a-zA-Z_]\w*|\[\d+\])*$/;
-var identifier = new RegExp(`${literal.source}|${variable.source}`, 'i');
-
-exports.patterns = {
-    quoted, number, bool, range, literal
-};
-
-exports.isLiteral = function(str) {
-    return literal.test(str);
-};
-
-exports.isVariable = function(str) {
-    return variable.test(str);
-};
-
-exports.parseLiteral = function(str) {
-    var res;
-    if(res = str.match(number)){
-        return Number(str);
-    }
-    if(res = str.match(bool)){
-        return str.toLowerCase() === 'true';
-    }
-    if(res = str.match(quoted)){
-        return str.slice(1, -1);
-    }
-    if(res = str.match(range)){
-        return _.range(res[1], res[2]);
-    }
-};
diff --git a/index.js b/index.js
new file mode 100644
index 000000000..91a9ee3fd
--- /dev/null
+++ b/index.js
@@ -0,0 +1,10 @@
+const context = require('./context');
+const tokenizer = require('./tokenizer.js');
+const render = require('./render.js');
+const lexical = require('./lexical.js');
+
+exports.render = function(html, ctx){
+    return render(tokenizer(html), context.factory(ctx));
+};
+
+exports.lexical = lexical;
diff --git a/lexical.js b/lexical.js
new file mode 100644
index 000000000..f309d1e4b
--- /dev/null
+++ b/lexical.js
@@ -0,0 +1,54 @@
+const _ = require('lodash');
+
+var singleQuoted = /'[^']*'/;
+var doubleQuoted = /"[^"]*"/;
+
+var number = /\d+\.?\d*|\.?\d+/;
+var bool = /true|false/i;
+var range = /\((\d+)\.\.(\d+)\)/;
+var identifier = /[a-zA-Z_$][a-zA-Z_$0-9]*/;
+var subscript = /\[\d+\]/;
+
+var quoted = new RegExp(`${singleQuoted.source}|${doubleQuoted.source}`);
+var literal = new RegExp(`${quoted.source}|${range.source}|${bool.source}|${number.source}`, 'i');
+var variable = new RegExp(`${identifier.source}(?:\\.${identifier.source}|${subscript.source})*`);
+var value = new RegExp(`${literal.source}|${variable.source}`, 'i');
+var hash = new RegExp(`(${identifier.source})\\s*:\\s*(${value.source})`, 'g');
+var filter = new RegExp(`(${identifier.source})(?:\\s*:\\s*(${value.source}))?`);
+
+var literalLine = new RegExp(`^(?:${literal.source})$`, 'i');
+var variableLine = new RegExp(`^(?:${variable.source})$`);
+var numberLine = new RegExp(`^(?:${number.source})$`);
+var boolLine = new RegExp(`^(?:${bool.source})$`, 'i');
+var quotedLine = new RegExp(`^(?:${quoted.source})$`);
+var rangeLine = new RegExp(`^(?:${range.source})$`);
+var filterLine = new RegExp(`^(?:${filter.source})$`);
+
+exports.patterns = {
+    quoted, number, bool, range, literal, hash, filter, identifier,
+    quotedLine, numberLine, boolLine, rangeLine, literalLine, filterLine
+};
+
+exports.isLiteral = function(str) {
+    return literalLine.test(str);
+};
+
+exports.isVariable = function(str) {
+    return variableLine.test(str);
+};
+
+exports.parseLiteral = function(str) {
+    var res;
+    if (res = str.match(numberLine)) {
+        return Number(str);
+    }
+    if (res = str.match(boolLine)) {
+        return str.toLowerCase() === 'true';
+    }
+    if (res = str.match(quotedLine)) {
+        return str.slice(1, -1);
+    }
+    if (res = str.match(rangeLine)) {
+        return _.range(res[1], res[2]);
+    }
+};
diff --git a/package.json b/package.json
index d9a30252d..43fb96321 100644
--- a/package.json
+++ b/package.json
@@ -21,15 +21,14 @@
   },
   "homepage": "https://github.com/harttle/shopify-liquid#readme",
   "dependencies": {
-    "bluebird": "^3.4.0",
     "lodash": "^4.13.1"
   },
   "devDependencies": {
     "chai": "^3.5.0",
-    "chai-as-promised": "^5.3.0",
     "coveralls": "^2.11.9",
     "istanbul": "^0.4.3",
     "mocha": "^2.5.3",
-    "sinon": "^1.17.4"
+    "sinon": "^1.17.4",
+    "sinon-chai": "^2.8.0"
   }
 }
diff --git a/render.js b/render.js
new file mode 100644
index 000000000..cc0c77c30
--- /dev/null
+++ b/render.js
@@ -0,0 +1,46 @@
+const Filter = require('./filter');
+const Tag = require('./tag');
+
+module.exports = function render(tokens, ctx) {
+    var html = '';
+    for (var i = 0; i < tokens.length; i++) {
+        var token = tokens.shift();
+        switch (token.type) {
+            case 'html':
+                html += token.value;
+                break;
+            case 'output':
+                html += renderOutput(token);
+                break;
+            case 'tag':
+                html += renderTag(token);
+                break;
+            default:
+                throw new Error(`unexpected type: ${token.type}`);
+        }
+    }
+    return html;
+
+    function renderOutput(token) {
+        var filters = token.value.split('|');
+        var val = ctx.get(filters.shift());
+        return filters
+            .map(str => Filter.parse(str))
+            .reduce((v, filter) => filter.render(v, ctx), val);
+    }
+
+    function renderTag(token) {
+        var tag = Tag.parse(token.value), subTokens = [];
+        if(tag.needClose){
+            var curToken, endToken = 'end' + tag.name;
+            while((curToken = tokens.shift()).value !== endToken){
+                subTokens.push(curToken);
+            }
+            if(curToken.value !== endToken){
+                throw new Error(`${token.value} not closed`);
+            }
+        }
+        return tag.render(subTokens, ctx);
+    }
+};
+
diff --git a/tag.js b/tag.js
new file mode 100644
index 000000000..8787d455f
--- /dev/null
+++ b/tag.js
@@ -0,0 +1,57 @@
+const lexical = require('./lexical.js');
+const context = require('./context.js');
+
+var tags = {};
+
+var _tagInstance = {
+    render: function(tokens, ctx){
+        var obj = hash(this.markup, ctx);
+        return this.tag.render(tokens, ctx, this.markup, obj);
+    }
+};
+
+function register(name, tag){
+    if(typeof tag.render !== 'function'){
+        throw new Error(`expect ${name}.render to be a function`);
+    }
+    tags[name] = tag;
+}
+
+function parse(str){
+    var match = lexical.patterns.identifier.exec(str.trim());
+    if(!match) throw new Error('illegal tag: '+ str);
+
+    var tagInstance = factory(match[0], str);
+    return tagInstance;
+}
+
+function hash(markup, ctx){
+    var obj = {};
+    lexical.patterns.hash.lastIndex = 0;
+    while(match = lexical.patterns.hash.exec(markup)){
+        var k = match[1], v = match[2];
+        if(!k) continue;
+        obj[k] = ctx.get(v);
+    }
+    return obj;
+}
+
+function factory(name, markup){
+    var tag = tags[name];
+    if(!tag) throw new Error(`tag ${name} not found`);
+    
+    var instance = Object.create(_tagInstance);
+    instance.name = name;
+    instance.markup = markup;
+    instance.tag = tag;
+    return instance;
+}
+
+function clear(){
+    tags = {};
+}
+
+exports.parse = parse;
+exports.register = register;
+exports.hash = hash;
+exports.clear = clear;
diff --git a/test/context.js b/test/context.js
index 17ba67411..325cddb86 100644
--- a/test/context.js
+++ b/test/context.js
@@ -1,6 +1,6 @@
 var chai = require("chai");
 var should = chai.should();
-chai.use(require("chai-as-promised"));
+var expect = chai.expect;
 
 var context = require('../context.js');
 
@@ -29,9 +29,17 @@ describe('context', function() {
         ctx.get('bar[1].b[1]').should.equal(2);
     });
 
-    it('should merge context', function() {
-        ctx.merge({foo: 'foo', foo1: 'foo1'});
+    it('should push context', function() {
+        ctx.push({foo: 'foo', foo1: 'foo1'});
         ctx.get('foo').should.equal('foo');
         ctx.get('foo1').should.equal('foo1');
+        ctx.get('bar[1].b[1]').should.equal(2);
+    });
+
+    it('should pop context', function() {
+        ctx.pop();
+        expect(ctx.get('foo')).to.equal('bar');
+        expect(ctx.get('foo1')).to.equal('');
+        expect(ctx.get('bar[1].b[1]')).to.equal(2);
     });
 });
diff --git a/test/filter.js b/test/filter.js
new file mode 100644
index 000000000..5f4fe9e18
--- /dev/null
+++ b/test/filter.js
@@ -0,0 +1,34 @@
+const chai = require("chai");
+const sinon = require("sinon");
+const sinonChai = require("sinon-chai");
+const expect = chai.expect;
+
+chai.use(sinonChai);
+
+var filter = require('../filter.js');
+var context = require('../context.js');
+
+describe('filter', function() {
+    var ctx;
+    beforeEach(function(){
+        filter.clear();
+        ctx = context.factory();
+    });
+    it('should throw when not registered', function() {
+        expect(function() {
+            filter.parse('foo');
+        }).to.throw(/filter foo not found/);
+    });
+
+    it('should register a simple filter', function(){
+        filter.register('foo', x => x.toUpperCase());
+        expect(filter.parse('foo').render('foo', ctx)).to.equal('FOO');
+    });
+
+    it('should call filter with corrct arguments', function(){
+        var spy = sinon.spy();
+        filter.register('foo', spy);
+        filter.parse('foo: 33').render('foo', ctx);
+        expect(spy).to.have.been.calledWith('foo', 33);
+    });
+});
diff --git a/test/identifier.js b/test/lexical.js
similarity index 98%
rename from test/identifier.js
rename to test/lexical.js
index 072022fa7..01cc44c9f 100644
--- a/test/identifier.js
+++ b/test/lexical.js
@@ -2,7 +2,7 @@ var chai = require("chai");
 var should = chai.should();
 chai.use(require("chai-as-promised"));
 
-var identifier = require('../identifier.js');
+var identifier = require('../lexical.js');
 
 describe('identifier', function() {
     it('should test boolean literal', function() {
diff --git a/test/render.js b/test/render.js
new file mode 100644
index 000000000..5e63ac044
--- /dev/null
+++ b/test/render.js
@@ -0,0 +1,79 @@
+const chai = require("chai");
+const sinonChai = require("sinon-chai");
+const sinon = require("sinon");
+const expect = chai.expect;
+
+chai.use(sinonChai);
+
+var tag = require('../tag.js');
+var context = require('../context.js');
+var filter = require('../filter');
+var render = require('../render.js');
+
+describe('render', function() {
+    var ctx, htmlToken, tagToken, filterToken;
+
+    before(function() {
+        ctx = context.factory({
+            x: 'XXX',
+            foo: {
+                bar: ['a', 2]
+            }
+        });
+        tagToken = {
+            type: 'tag',
+            value: 'foo bar:x foo:"FOO" num:2.3'
+        };
+        htmlToken = {
+            type: 'html',
+            value: '<p>'
+        };
+        filterToken = {
+            type: 'output',
+            value: 'foo.bar[0] | date: "b" | time:2'
+        };
+    });
+
+    beforeEach(function(){
+        filter.clear();
+        tag.clear();
+    });
+
+    it('should render html', function() {
+        expect(render([htmlToken], ctx)).to.equal('<p>');
+    });
+
+    it('should render with tag function', function() {
+        tag.register('foo', {
+            render: x => 'X'
+        });
+        expect(render([tagToken], ctx)).to.equal('X');
+    });
+
+    it('should call tag with correct arguments', function() {
+        var spy = sinon.spy();
+        tag.register('foo', { render: spy });
+        render([tagToken], ctx);
+        expect(spy).to.have.been.calledWithMatch([], ctx, tagToken.value, {
+            bar: 'XXX',
+            foo: 'FOO',
+            num: 2.3
+        });
+    });
+
+    it('should render with filter function', function() {
+        filter.register('date', (l, r) => l + r);
+        filter.register('time', (l, r) => l + 3*r);
+        expect(render([filterToken], ctx)).to.equal('ab6');
+    });
+
+    it('should call filter with correct arguments', function() {
+        var date = sinon.stub().returns('y');
+        var time = sinon.spy();
+        filter.register('date', date);
+        filter.register('time', time);
+        render([filterToken], ctx);
+        expect(date).to.have.been.calledWith('a', 'b');
+        expect(time).to.have.been.calledWith('y', 2);
+    });
+});
diff --git a/test/tag.js b/test/tag.js
new file mode 100644
index 000000000..0c2003996
--- /dev/null
+++ b/test/tag.js
@@ -0,0 +1,65 @@
+var chai = require("chai");
+var sinonChai = require("sinon-chai");
+var sinon = require("sinon");
+var expect = chai.expect;
+chai.use(sinonChai);
+
+var tag = require('../tag.js');
+var context = require('../context.js');
+
+describe('tag', function() {
+    var ctx;
+    before(function(){
+        ctx = context.factory({
+            foo: 'bar',
+            arr: [2, 1]
+        });
+        tag.clear();
+    });
+
+    it('should throw when not registered', function() {
+        expect(function() {
+            tag.parse('foo');
+        }).to.throw(/tag foo not found/);
+    });
+
+    it('should throw when render method not defined', function() {
+        expect(function() {
+            tag.register('foo', {});
+        }).to.throw(/expect foo.render to be a function/);
+    });
+
+    it('should register simple tag', function() {
+        expect(
+            function() {
+                tag.register('foo', {
+                    render: x => 'bar'
+                });
+            }).not.throw();
+    });
+
+    it('should call tag.render', function() {
+        var spy = sinon.spy(),
+            tokens = [];
+        tag.register('foo', {
+            render: spy
+        });
+        tag.parse('foo').render(tokens, ctx);
+        expect(spy).to.have.been.called;
+    });
+
+    it('should call tag.render with resolved hash', function() {
+        var spy = sinon.spy(),
+            tokens = [];
+        tag.register('foo', {
+            render: spy
+        });
+        var t = tag.parse('foo aa:foo bb: arr[0] cc: 2.3');
+        t.render(tokens, ctx);
+        expect(spy).to.have.been.calledWithMatch(tokens, ctx, 'foo', {
+            aa: 'bar',
+            bb: 2,
+            cc: 2.3
+        });
+    });
+});
diff --git a/test/tokenizer.js b/test/tokenizer.js
index 2b2374f2d..a4d7db627 100644
--- a/test/tokenizer.js
+++ b/test/tokenizer.js
@@ -1,6 +1,5 @@
 var chai = require("chai");
 var should = chai.should();
-chai.use(require("chai-as-promised"));
 
 var tokenizer = require('../tokenizer.js');