diff --git a/ASTJsonConverter.cpp b/ASTJsonConverter.cpp
index c30e4ca2b..be89de924 100644
--- a/ASTJsonConverter.cpp
+++ b/ASTJsonConverter.cpp
@@ -78,10 +78,16 @@ ASTJsonConverter::ASTJsonConverter(ASTNode const& _ast): m_ast(&_ast)
 
 void ASTJsonConverter::print(ostream& _stream)
 {
-	m_ast->accept(*this);
+	process();
 	_stream << m_astJson;
 }
 
+Json::Value const& ASTJsonConverter::json()
+{
+	process();
+	return m_astJson;
+}
+
 bool ASTJsonConverter::visit(ImportDirective const& _node)
 {
 	addJsonNode("Import", { make_pair("file", _node.getIdentifier())});
@@ -460,9 +466,16 @@ void ASTJsonConverter::endVisit(Literal const&)
 {
 }
 
+void ASTJsonConverter::process()
+{
+	if (!processed)
+		m_ast->accept(*this);
+	processed = true;
+}
+
 string ASTJsonConverter::getType(Expression const& _expression)
 {
-	return  (_expression.getType()) ? _expression.getType()->toString() : "Unknown";
+	return (_expression.getType()) ? _expression.getType()->toString() : "Unknown";
 }
 
 }
diff --git a/ASTJsonConverter.h b/ASTJsonConverter.h
index 30a92e66c..56502ab3c 100644
--- a/ASTJsonConverter.h
+++ b/ASTJsonConverter.h
@@ -44,6 +44,7 @@ public:
 	ASTJsonConverter(ASTNode const& _ast);
 	/// Output the json representation of the AST to _stream.
 	void print(std::ostream& _stream);
+	Json::Value const& json();
 
 	bool visit(ImportDirective const& _node) override;
 	bool visit(ContractDefinition const& _node) override;
@@ -114,6 +115,7 @@ public:
 	void endVisit(Literal const&) override;
 
 private:
+	void process();
 	void addKeyValue(Json::Value& _obj, std::string const& _key, std::string const& _val);
 	void addJsonNode(std::string const& _nodeName,
 					 std::initializer_list<std::pair<std::string const, std::string const>> _list,
@@ -123,8 +125,9 @@ private:
 	{
 		solAssert(!m_jsonNodePtrs.empty(), "Uneven json nodes stack. Internal error.");
 		m_jsonNodePtrs.pop();
-	};
+	}
 
+	bool processed = false;
 	Json::Value m_astJson;
 	std::stack<Json::Value*> m_jsonNodePtrs;
 	std::string m_source;
diff --git a/Compiler.h b/Compiler.h
index d476ec684..c3c3b9dcc 100644
--- a/Compiler.h
+++ b/Compiler.h
@@ -43,9 +43,9 @@ public:
 	bytes getRuntimeBytecode() { return m_runtimeContext.getAssembledBytecode(m_optimize);}
 	/// @arg _sourceCodes is the map of input files to source code strings
 	/// @arg _inJsonFromat shows whether the out should be in Json format
-	void streamAssembly(std::ostream& _stream, StringMap const& _sourceCodes = StringMap(), bool _inJsonFormat = false) const
+	Json::Value streamAssembly(std::ostream& _stream, StringMap const& _sourceCodes = StringMap(), bool _inJsonFormat = false) const
 	{
-		m_context.streamAssembly(_stream, _sourceCodes, _inJsonFormat);
+		return m_context.streamAssembly(_stream, _sourceCodes, _inJsonFormat);
 	}
 	/// @returns Assembly items of the normal compiler context
 	eth::AssemblyItems const& getAssemblyItems() const { return m_context.getAssembly().getItems(); }
diff --git a/CompilerContext.h b/CompilerContext.h
index 34a3f97cd..0ca6369dd 100644
--- a/CompilerContext.h
+++ b/CompilerContext.h
@@ -123,9 +123,9 @@ public:
 	eth::Assembly const& getAssembly() const { return m_asm; }
 	/// @arg _sourceCodes is the map of input files to source code strings
 	/// @arg _inJsonFormat shows whether the out should be in Json format
-	void streamAssembly(std::ostream& _stream, StringMap const& _sourceCodes = StringMap(), bool _inJsonFormat = false) const
+	Json::Value streamAssembly(std::ostream& _stream, StringMap const& _sourceCodes = StringMap(), bool _inJsonFormat = false) const
 	{
-		m_asm.stream(_stream, "", _sourceCodes, _inJsonFormat);
+		return m_asm.stream(_stream, "", _sourceCodes, _inJsonFormat);
 	}
 
 	bytes getAssembledBytecode(bool _optimize = false) { return m_asm.optimise(_optimize).assemble(); }
diff --git a/CompilerStack.cpp b/CompilerStack.cpp
index d6274e2c7..a2a178317 100644
--- a/CompilerStack.cpp
+++ b/CompilerStack.cpp
@@ -184,13 +184,16 @@ dev::h256 CompilerStack::getContractCodeHash(string const& _contractName) const
 	return dev::sha3(getRuntimeBytecode(_contractName));
 }
 
-void CompilerStack::streamAssembly(ostream& _outStream, string const& _contractName, StringMap _sourceCodes, bool _inJsonFormat) const
+Json::Value CompilerStack::streamAssembly(ostream& _outStream, string const& _contractName, StringMap _sourceCodes, bool _inJsonFormat) const
 {
 	Contract const& contract = getContract(_contractName);
 	if (contract.compiler)
-		contract.compiler->streamAssembly(_outStream, _sourceCodes, _inJsonFormat);
+		return contract.compiler->streamAssembly(_outStream, _sourceCodes, _inJsonFormat);
 	else
+	{
 		_outStream << "Contract not fully implemented" << endl;
+		return Json::Value();
+	}
 }
 
 string const& CompilerStack::getInterface(string const& _contractName) const
diff --git a/CompilerStack.h b/CompilerStack.h
index 2e7c217d5..6f90a846e 100644
--- a/CompilerStack.h
+++ b/CompilerStack.h
@@ -28,6 +28,7 @@
 #include <memory>
 #include <vector>
 #include <boost/noncopyable.hpp>
+#include <json/json.h>
 #include <libdevcore/Common.h>
 #include <libdevcore/FixedHash.h>
 
@@ -104,7 +105,7 @@ public:
 	/// @arg _sourceCodes is the map of input files to source code strings
 	/// @arg _inJsonFromat shows whether the out should be in Json format
 	/// Prerequisite: Successful compilation.
-	void streamAssembly(std::ostream& _outStream, std::string const& _contractName = "", StringMap _sourceCodes = StringMap(), bool _inJsonFormat = false) const;
+	Json::Value streamAssembly(std::ostream& _outStream, std::string const& _contractName = "", StringMap _sourceCodes = StringMap(), bool _inJsonFormat = false) const;
 
 	/// Returns a string representing the contract interface in JSON.
 	/// Prerequisite: Successful call to parse or compile.