diff --git a/alethzero/MainWin.cpp b/alethzero/MainWin.cpp
index 6e5661190..f2418dbb0 100644
--- a/alethzero/MainWin.cpp
+++ b/alethzero/MainWin.cpp
@@ -434,6 +434,12 @@ QVariant Main::evalRaw(QString const& _js)
 	return ui->webView->page()->currentFrame()->evaluateJavaScript(_js);
 }
 
+void Main::addToWindowObject(QObject* _object, QString const& _name)
+{
+	QWebFrame* f = ui->webView->page()->mainFrame();
+	f->addToJavaScriptWindowObject(_name, _object, QWebFrame::QtOwnership);
+}
+
 void Main::eval(QString const& _js)
 {
 	if (_js.trimmed().isEmpty())
diff --git a/alethzero/MainWin.h b/alethzero/MainWin.h
index 6f8ee7e2b..37ec8f7c1 100644
--- a/alethzero/MainWin.h
+++ b/alethzero/MainWin.h
@@ -91,6 +91,7 @@ public:
 	QList<dev::KeyPair> owned() const { return m_myIdentities + m_myKeys; }
 	
 	QVariant evalRaw(QString const& _js);
+	void addToWindowObject(QObject* _object, QString const& _name);
 
 public slots:
 	void load(QString _file);
diff --git a/alethzero/OurWebThreeStubServer.cpp b/alethzero/OurWebThreeStubServer.cpp
index 843ed2baf..4769ab3ff 100644
--- a/alethzero/OurWebThreeStubServer.cpp
+++ b/alethzero/OurWebThreeStubServer.cpp
@@ -21,9 +21,13 @@
 
 #include "OurWebThreeStubServer.h"
 
+#include <QtCore/QString>
+#include <QtCore/QtCore>
 #include <QMessageBox>
 #include <QAbstractButton>
 #include <libwebthree/WebThree.h>
+#include <jsoncpp/json/json.h>
+
 #include "MainWin.h"
 
 using namespace std;
@@ -54,7 +58,7 @@ bool OurWebThreeStubServer::showAuthenticationPopup(std::string const& _title, s
 	return userInput.exec() == QMessageBox::Ok;
 }
 
-bool OurWebThreeStubServer::authenticate(dev::TransactionSkeleton const& _t) const
+bool OurWebThreeStubServer::authenticate(dev::TransactionSkeleton const& _t)
 {
 	h256 contractCodeHash = m_web3->ethereum()->postState().codeHash(_t.to);
 	if (contractCodeHash == EmptySHA3)
@@ -69,15 +73,15 @@ bool OurWebThreeStubServer::authenticate(dev::TransactionSkeleton const& _t) con
 //		return showAuthenticationPopup("Unverified Pending Transaction",
 //									   "An undocumented transaction is about to be executed.");
 
-	QNatspecExpressionEvaluator evaluator(*m_web3, m_main);
+	QNatspecExpressionEvaluator evaluator(this, m_main);
 	userNotice = evaluator.evalExpression(QString::fromStdString(userNotice)).toStdString();
 
 	// otherwise it's a transaction to a contract for which we have the natspec
 	return showAuthenticationPopup("Pending Transaction", userNotice);
 }
 
-QNatspecExpressionEvaluator::QNatspecExpressionEvaluator(dev::WebThreeDirect& _web3, Main* _main):
-	m_web3(&_web3), m_main(_main)
+QNatspecExpressionEvaluator::QNatspecExpressionEvaluator(OurWebThreeStubServer* _server, Main* _main)
+: m_server(_server), m_main(_main)
 {}
 
 QNatspecExpressionEvaluator::~QNatspecExpressionEvaluator()
@@ -85,20 +89,35 @@ QNatspecExpressionEvaluator::~QNatspecExpressionEvaluator()
 
 QString QNatspecExpressionEvaluator::stateAt(QString _key)
 {
+	(void)_key;
 	return "1";
 }
 
-QString QNatspecExpressionEvaluator::call(QString _method)
+QString QNatspecExpressionEvaluator::call(QString _json)
+{
+	QJsonObject jsonObject = QJsonDocument::fromJson(_json.toUtf8()).object();
+	Json::Value input;
+	input["to"] = jsonObject["to"].toString().toStdString();
+	input["data"] = jsonObject["data"].toString().toStdString();
+	return QString::fromStdString(m_server->eth_call(input));
+}
+
+QString QNatspecExpressionEvaluator::sha3(QString _method)
 {
-	return "2";
+	return QString::fromStdString(m_server->web3_sha3(_method.toStdString()));
 }
 
 QString QNatspecExpressionEvaluator::evalExpression(QString const& _expression)
 {
+	
 	// evaluate the natspec
+	m_main->addToWindowObject(this, "_natspec");
 	m_main->evalRaw(contentsOfQResource(":/js/natspec.js"));
-	auto result = m_main->evalRaw("evaluateExpression(\"2 + 1\")");
+	
+	(void)_expression;
+	auto result = m_main->evalRaw(QString::fromStdString((string)"evaluateExpression('" + "multiply(4)" + "')"));
 //	auto result = m_main->evalRaw(_expression);
+	
 	return result.toString();
 }
 
diff --git a/alethzero/OurWebThreeStubServer.h b/alethzero/OurWebThreeStubServer.h
index fe7d432cf..384b5591b 100644
--- a/alethzero/OurWebThreeStubServer.h
+++ b/alethzero/OurWebThreeStubServer.h
@@ -35,7 +35,7 @@ public:
 						  std::vector<dev::KeyPair> const& _accounts, Main* main);
 
 	virtual std::string shh_newIdentity() override;
-	virtual bool authenticate(dev::TransactionSkeleton const& _t) const;
+	virtual bool authenticate(dev::TransactionSkeleton const& _t);
 
 signals:
 	void onNewId(QString _s);
@@ -53,15 +53,16 @@ class QNatspecExpressionEvaluator: public QObject
 	Q_OBJECT
 	
 public:
-	QNatspecExpressionEvaluator(dev::WebThreeDirect& _web3, Main* _main);
+	QNatspecExpressionEvaluator(OurWebThreeStubServer* _server, Main* _main);
 	virtual ~QNatspecExpressionEvaluator();
 	
 	QString evalExpression(QString const& _expression);
 	
 	Q_INVOKABLE QString stateAt(QString _key);
-	Q_INVOKABLE QString call(QString _method);
+	Q_INVOKABLE QString call(QString _json);
+	Q_INVOKABLE QString sha3(QString _method);
 	
 private:
-	dev::WebThreeDirect* m_web3;
+	OurWebThreeStubServer* m_server;
 	Main* m_main;
 };
\ No newline at end of file
diff --git a/libjsqrc/ethereumjs/example/natspec_contract.html b/libjsqrc/ethereumjs/example/natspec_contract.html
index 2548495b7..2cf641910 100644
--- a/libjsqrc/ethereumjs/example/natspec_contract.html
+++ b/libjsqrc/ethereumjs/example/natspec_contract.html
@@ -5,6 +5,7 @@
 <script type="text/javascript" src="js/es6-promise/promise.min.js"></script>
 <script type="text/javascript" src="js/bignumber.js/bignumber.min.js"></script>
 <script type="text/javascript" src="../dist/ethereum.js"></script>
+<script type="text/javascript" src="../../natspec.js"></script>
 <script type="text/javascript">
 
     var web3 = require('web3');
@@ -13,7 +14,7 @@
     // solidity source code
     var source = "" + 
     "contract test {\n" +
-    "   /// @notice Will multiplty `a` by 7. \n" +
+    "   /// @notice Will multiply `a` by 7. \n" +
     "   function multiply(uint a) returns(uint d) {\n" +
     "       return a * 7;\n" +
     "   }\n" +
@@ -21,7 +22,7 @@
 
     // contract description, this will be autogenerated somehow
     var desc =  [{
-        "name": "multiply",
+        "name": "multiply(uint256)",
         "inputs": [
         {
             "name": "a",
diff --git a/libjsqrc/natspec.js b/libjsqrc/natspec.js
index 0807fecb8..457a487a0 100644
--- a/libjsqrc/natspec.js
+++ b/libjsqrc/natspec.js
@@ -1,7 +1,12 @@
 
 /**
- * This plugin should be reloaded each time we want to evaluate set of expressions
+ * This plugin exposes 'evaluateExpression' method which should be used
+ * to evaluate natspec description
+ * It should be reloaded each time we want to evaluate set of expressions
  * Just because of security reasons
+ * TODO: make use of sync api (once it's finished) and remove unnecessary 
+ * code from 'getContractMethods'
+ * TODO: unify method signature creation with abi.js (and make a separate method from it)
  */
 
 /// Should be called to copy values from object to global context
@@ -15,25 +20,41 @@ var copyToContext = function (obj, context) {
 /// Function called to get all contract's storage values
 /// @returns hashmap with contract properties which are used
 var getContractProperties = function (expression, abi) {
-    var keys = ['test'];
-
-    return keys.reduce(function (acc, current) {
-        acc[current] = natspec.stateAt(current);
-        return acc;
-    }, {});
+    return {};
 };
 
 /// Function called to get all contract's methods
 /// @returns hashmap with used contract's methods
-var getContractMethods = function (expression, abi) {
-    var keys = ['testMethod'];
+var getContractMethods = function (address, abi) {
+
+    var contract = {};
+    var inputParser = web3.abi.inputParser(abi);
+    var outputParser = web3.abi.outputParser(abi);
+
+    abi.forEach(function (method) {
+
+        var displayName = web3.abi.methodDisplayName(method.name);
+        var typeName = web3.abi.methodTypeName(method.name);
 
-    return keys.reduce(function (acc, current) {
-        acc[current] = function () {
-            // TODO: connect parser
+        var impl = function () {
+            var params = Array.prototype.slice.call(arguments);
+            var parsed = inputParser[displayName][typeName].apply(null, params);
+            var methodSignature = _natspec.sha3(web3.fromAscii(method.name)).slice(0, 10);
+            var output = _natspec.call(JSON.stringify({
+                to: address,
+                data: methodSignature + parsed
+            }));
+            return outputParser[displayName][typeName](output);
         };
-        return acc;
-    }, {});
+
+        if (contract[displayName] === undefined) {
+            contract[displayName] = impl;
+        }
+
+        contract[displayName][typeName] = impl;
+    });
+
+    return contract; 
 };
 
 /// Should be called to evaluate single expression
@@ -42,15 +63,16 @@ var getContractMethods = function (expression, abi) {
 var evaluateExpression = function (expression) {
 
     var self = this;
-    var abi = web3._currentAbi;
+    var abi = web3._currentContractAbi;
+    var address = web3._currentContractAddress;
 
     var storage = getContractProperties(expression, abi); 
-    var methods = getContractMethods(expression, abi);
+    var methods = getContractMethods(address, abi);
 
     copyToContext(storage, self);
     copyToContext(methods, self);
 
-    // TODO: check if it is safe
+    // TODO: test if it is safe
     return eval(expression).toString();
 };
 
diff --git a/libweb3jsonrpc/WebThreeStubServerBase.cpp b/libweb3jsonrpc/WebThreeStubServerBase.cpp
index 640ad3679..4acf76ef9 100644
--- a/libweb3jsonrpc/WebThreeStubServerBase.cpp
+++ b/libweb3jsonrpc/WebThreeStubServerBase.cpp
@@ -631,7 +631,7 @@ std::string WebThreeStubServerBase::eth_transact(Json::Value const& _json)
 	return ret;
 }
 
-bool WebThreeStubServerBase::authenticate(TransactionSkeleton const& _t) const
+bool WebThreeStubServerBase::authenticate(TransactionSkeleton const& _t)
 {
 	cwarn << "Silently signing transaction from address" << _t.from.abridged() << ": User validation hook goes here.";
 	return true;
diff --git a/libweb3jsonrpc/WebThreeStubServerBase.h b/libweb3jsonrpc/WebThreeStubServerBase.h
index 24a6a9962..7aeba0f81 100644
--- a/libweb3jsonrpc/WebThreeStubServerBase.h
+++ b/libweb3jsonrpc/WebThreeStubServerBase.h
@@ -121,7 +121,7 @@ public:
 	std::map<dev::Public, dev::Secret> const& ids() const { return m_ids; }
 
 protected:
-	virtual bool authenticate(dev::TransactionSkeleton const& _t) const;
+	virtual bool authenticate(dev::TransactionSkeleton const& _t);
 
 protected:
 	virtual dev::eth::Interface* client() = 0;