diff --git a/src/serializer.h b/src/serializer.h
index 3973e968..2edaa809 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -39,8 +39,8 @@ class Writer {
 
   virtual void Null() = 0;
   virtual void Bool(bool x) = 0;
-  virtual void Int(uint64_t x) = 0;
-  virtual void Int64(uint64_t x) = 0;
+  virtual void Int(int x) = 0;
+  virtual void Int64(int64_t x) = 0;
   virtual void Uint64(uint64_t x) = 0;
   virtual void String(const char* x) = 0;
   virtual void String(const char* x, size_t len) = 0;
diff --git a/src/serializers/json.h b/src/serializers/json.h
new file mode 100644
index 00000000..ed345234
--- /dev/null
+++ b/src/serializers/json.h
@@ -0,0 +1,68 @@
+#pragma once
+
+#include "serializer.h"
+
+#include <rapidjson/document.h>
+#include <rapidjson/prettywriter.h>
+
+class JsonReader : public Reader {
+  rapidjson::GenericValue<rapidjson::UTF8<>>* m_;
+
+ public:
+  JsonReader(rapidjson::GenericValue<rapidjson::UTF8<>>* m) : m_(m) {}
+
+  bool IsBool() override { return m_->IsBool(); }
+  bool IsNull() override { return m_->IsNull(); }
+  bool IsArray() override { return m_->IsArray(); }
+  bool IsInt() override { return m_->IsInt(); }
+  bool IsInt64() override { return m_->IsInt64(); }
+  bool IsUint64() override { return m_->IsUint64(); }
+  bool IsString() override { return m_->IsString(); }
+
+  bool GetBool() override { return m_->GetBool(); }
+  int GetInt() override { return m_->GetInt(); }
+  int64_t GetInt64() override { return m_->GetInt64(); }
+  uint64_t GetUint64() override { return m_->GetUint64(); }
+  const char* GetString() override { return m_->GetString(); }
+
+  bool HasMember(const char* x) override { return m_->HasMember(x); }
+  std::unique_ptr<Reader> operator[](const char* x) override {
+    auto& sub = (*m_)[x];
+    return std::unique_ptr<JsonReader>(new JsonReader(&sub));
+  }
+
+  void IterArray(std::function<void(Reader&)> fn) override {
+    for (auto& entry : m_->GetArray()) {
+      JsonReader sub(&entry);
+      fn(sub);
+    }
+  }
+
+  void DoMember(const char* name, std::function<void(Reader&)> fn) override {
+    auto it = m_->FindMember(name);
+    if (it != m_->MemberEnd()) {
+      JsonReader sub(&it->value);
+      fn(sub);
+    }
+  }
+};
+
+class JsonWriter : public Writer {
+  rapidjson::Writer<rapidjson::StringBuffer>* m_;
+
+ public:
+  JsonWriter(rapidjson::Writer<rapidjson::StringBuffer>* m) : m_(m) {}
+
+  void Null() override { m_->Null(); }
+  void Bool(bool x) override { m_->Bool(x); }
+  void Int(int x) override { m_->Int(x); }
+  void Int64(int64_t x) override { m_->Int64(x); }
+  void Uint64(uint64_t x) override { m_->Uint64(x); }
+  void String(const char* x) override { m_->String(x); }
+  void String(const char* x, size_t len) override { m_->String(x, len); }
+  void StartArray() override { m_->StartArray(); }
+  void EndArray() override { m_->EndArray(); }
+  void StartObject() override { m_->StartObject(); }
+  void EndObject() override { m_->EndObject(); }
+  void Key(const char* name) override { m_->Key(name); }
+};