diff --git a/.gitignore b/.gitignore
index 0898aed..141bb68 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
 build/
 .kdev4/
 *.kdev4
+deps/
+tags
diff --git a/.vimrc b/.vimrc
new file mode 100644
index 0000000..371c485
--- /dev/null
+++ b/.vimrc
@@ -0,0 +1,10 @@
+set colorcolumn=110
+highlight ColorColumn ctermbg=darkgray
+augroup project
+  autocmd!
+  autocmd BufRead,BufNewFile *.h,*.c set filetype=c.doxygen
+augroup END
+nnoremap <F4> :!mkdir -p build <bar> cmake -B build <bar> make -C build<cr>
+nnoremap <F4> :!build/PiHelper/pihelper localhost<cr>
+nnoremap <F9> :!rm -rf build<cr>
+let &path.="/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include,"
diff --git a/budget.json b/budget.json
new file mode 100644
index 0000000..ab375dd
--- /dev/null
+++ b/budget.json
@@ -0,0 +1 @@
+{"id":"Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU","name":"Monthly Budget","description":"Monthly expenses"}
diff --git a/include/twigs/api_service.h b/include/twigs/api_service.h
new file mode 100644
index 0000000..e3bd250
--- /dev/null
+++ b/include/twigs/api_service.h
@@ -0,0 +1,3 @@
+#ifndef API_SERVICE_H
+#define API_SERVICE_H
+#endif
diff --git a/include/twigs/budget.h b/include/twigs/budget.h
index 80d86a5..4c39d5f 100644
--- a/include/twigs/budget.h
+++ b/include/twigs/budget.h
@@ -1,33 +1,28 @@
 #ifndef BUDGET_H
 #define BUDGET_H
-#include <string>
 #include "hashable.h"
 #include "identifiable.h"
+#include "serializable.h"
+#include <string>
 
 using namespace std;
 
-class Budget: public Identifiable, public Hashable {
-    private:
-        string name;
-        string description;
+class Budget : public Identifiable, public Hashable, public Serializable {
+private:
+  string id;
+  string name;
+  string description;
 
-    public:
-        string getName() {
-            return this->name;
-        }
-        
-        void setName(string name) {
-            this->name = name;
-        }
-        
-        string getDescription() {
-            return this->description;
-        }
-        
-        void setDescription(string description) {
-            this->description = description;
-        }
-        
-        string hash() override;
+public:
+  Budget();
+  Budget(std::string id, std::string name, std::string description);
+  string getId() override;
+  string getName();
+  void setName(string name);
+  string getDescription();
+  void setDescription(string description);
+  string hash() override;
+  string serialize() override;
+  static Budget deserialize(std::string data);
 };
 #endif
diff --git a/include/twigs/category.h b/include/twigs/category.h
index efca750..5fe3bf1 100644
--- a/include/twigs/category.h
+++ b/include/twigs/category.h
@@ -1,64 +1,38 @@
-#ifndef CATEGORY_H
 #define CATEGORY_H
-#include <string>
+#ifndef CATEGORY_H
 #include "hashable.h"
 #include "identifiable.h"
+#include "serializable.h"
+#include <string>
 
-class Category: public Identifiable, public Hashable {
-    private:
-        std::string id;
-        std::string name;
-        std::string description;
-        long amount;
-        bool expense;
-        bool archived;
-        std::string budgetId;
+class Category : public Identifiable, public Hashable, public Serializable {
+private:
+  std::string id;
+  std::string name;
+  std::string description;
+  unsigned int amount;
+  bool expense;
+  bool archived;
+  std::string budgetId;
 
-    public:
-        std::string getId() {
-            return this->id;
-        }
-        
-        std::string getName() {
-            return this->name;
-        }
-        
-        void setName(std::string name) {
-            this->name = name;
-        }
-        
-        std::string getDescription() {
-            return this->description;
-        }
-        
-        void setDescription(std::string description) {
-            this->description = description;
-        }
-        
-        long getAmount() {
-            return this->amount;
-        }
-        
-        void setAmount(long amount) {
-            this->amount = amount;
-        }
-        
-        bool isExpense() {
-            return this->expense;
-        }
-        
-        void setExpense(bool expense) {
-            this->expense = expense;
-        }
-        
-        bool isArchived() {
-            return this->archived;
-        }
-        
-        void setArchived(bool archived) {
-            this->archived = archived;
-        }
-        
-        std::string hash() override;
+public:
+  Category();
+  Category(std::string id, std::string name, std::string budgetId,
+           std::string description = "", unsigned int amount = 0,
+           bool expense = true, bool archived = false);
+  std::string getId() override;
+  std::string getName();
+  void setName(std::string name);
+  std::string getDescription();
+  void setDescription(std::string description);
+  unsigned int getAmount();
+  void setAmount(unsigned int amount);
+  bool isExpense();
+  void setExpense(bool expense);
+  bool isArchived();
+  void setArchived(bool archived);
+  std::string hash() override;
+  string serialize() override;
+  static Categpry deserialize(std::string data);
 };
 #endif
diff --git a/include/twigs/db_service.h b/include/twigs/db_service.h
new file mode 100644
index 0000000..046b294
--- /dev/null
+++ b/include/twigs/db_service.h
@@ -0,0 +1,4 @@
+#ifndef DB_SERVICE_H
+#define DB_SERVICE_H
+
+#endif
diff --git a/include/twigs/identifiable.h b/include/twigs/identifiable.h
index 9dcac11..3baab8e 100644
--- a/include/twigs/identifiable.h
+++ b/include/twigs/identifiable.h
@@ -3,15 +3,7 @@
 #include <string>
 
 class Identifiable {
-    private:
-        std::string id;
-    
     public:
-        std::string getId() {
-            return this->id;
-        }
-        void setId(std::string id) {
-            this->id = id;
-        }
+        virtual std::string getId() = 0;
 };
 #endif
diff --git a/include/twigs/permission.h b/include/twigs/permission.h
index db16c48..892e18a 100644
--- a/include/twigs/permission.h
+++ b/include/twigs/permission.h
@@ -13,6 +13,7 @@ enum Permission {
 
 class UserPermission: public Identifiable {
     private:
+        std::string id;
         std::string userId;
         std::string budgetId;
         Permission permission;
@@ -23,6 +24,8 @@ class UserPermission: public Identifiable {
             this->budgetId = budgetId;
         }
         
+        std::string getId() override;
+        
         std::string getUserId() {
             return this->userId;
         }
diff --git a/include/twigs/serializable.h b/include/twigs/serializable.h
new file mode 100644
index 0000000..20a5920
--- /dev/null
+++ b/include/twigs/serializable.h
@@ -0,0 +1,9 @@
+#ifndef SERIALIZABLE_H
+#define SERIALIZABLE_H
+#include <string>
+
+class Serializable {
+public:
+    virtual std::string serialize() = 0;
+};
+#endif
diff --git a/include/twigs/transaction.h b/include/twigs/transaction.h
index 36d947a..9bfdc84 100644
--- a/include/twigs/transaction.h
+++ b/include/twigs/transaction.h
@@ -1,113 +1,51 @@
 #ifndef TRANSACTION_H
 #define TRANSACTION_H
-#include <string>
-#include <stdio.h>
-#include <time.h>
 #include "hashable.h"
 #include "identifiable.h"
+#include "serializable.h"
+#include <stdio.h>
+#include <string>
+#include <time.h>
 
-using namespace std;
+class Transaction : public Identifiable, public Hashable, public Serializable {
+private:
+  std::string id;
+  std::string name;
+  std::string description;
+  tm date;
+  unsigned int amount;
+  bool expense;
+  std::string categoryId;
+  std::string budgetId;
+  std::string createdBy;
 
-class Transaction: public Identifiable, public Hashable {
-    private:
-        string name;
-        string description;
-        tm date;
-        long amount;
-        bool expense;
-        bool archived;
-        string categoryId;
-        string budgetId;
-
-    public:
-        Transaction() {
-            this->name = "";
-            this->description = "";
-            time_t now = time(0);
-            this->date = *gmtime(&now);
-            this->amount = 0;
-            this->expense = true;
-            this->archived = false;
-        }
-        
-        string getName() {
-            return this->name;
-        }
-        
-        void setName(string name) {
-            this->name = name;
-        }
-        
-        string getDescription() {
-            return this->description;
-        }
-        
-        void setDescription(string description) {
-            this->description = description;
-        }
-        
-        /**
-         * Returns the date as a string formatted as YYYY-MM-ddTHH:mm:ssZ
-         */
-        string getDate() {
-            char date[25];
-            snprintf(
-                date,
-                21,
-                "%04d-%02d-%02dT%02d:%02d:%02dZ",
-                this->date.tm_year,
-                this->date.tm_mon + 1,
-                this->date.tm_mday,
-                this->date.tm_hour,
-                this->date.tm_min,
-                this->date.tm_sec
-            );
-            return date;
-        }
-        
-        /**
-         * Sets the date using YYYY-MM-ddTHH:mm:ssZ format
-         */
-        void setDate(string date) {
-            //TODO: Handle exceptions
-            int year = stoi(date.substr(0,4));
-            int mon = stoi(date.substr(5, 2));
-            int day = stoi(date.substr(8, 2));
-            int hours = stoi(date.substr(11, 2));
-            int min = stoi(date.substr(14, 2));
-            int sec = stoi(date.substr(17, 2));
-            this->date.tm_year = year;
-            this->date.tm_mon = mon - 1;
-            this->date.tm_mday = day;
-            this->date.tm_hour = hours;
-            this->date.tm_min = min;
-            this->date.tm_sec = sec;
-        }
-        
-        long getAmount() {
-            return this->amount;
-        }
-        
-        void setAmount(long amount) {
-            this->amount = amount;
-        }
-        
-        bool isExpense() {
-            return this->expense;
-        }
-        
-        void setExpense(bool expense) {
-            this->expense = expense;
-        }
-        
-        bool isArchived() {
-            return this->archived;
-        }
-        
-        void setArchived(bool archived) {
-            this->archived = archived;
-        }
-        
-        string hash() override;
+public:
+  Transaction();
+  Transaction(std::string id, std::string name, tm date, std::string createdBy,
+              unsigned int amount = 0, std::string description = "",
+              bool expense = true, std::string categoryId = "",
+              std::string budgetId = "");
+  std::string getId() override;
+  std::string getName();
+  void setName(std::string name);
+  std::string getDescription();
+  void setDescription(std::string description);
+  tm getDate();
+  void setDate(tm date);
+  unsigned int getAmount();
+  void setAmount(unsigned int amount);
+  bool isExpense();
+  void setExpense(bool expense);
+  bool isArchived();
+  void setArchived(bool archived);
+  std::string getCategoryId();
+  void setCategoryId(std::string categoryId);
+  std::string getBudgetId();
+  void setBudgetId(std::string budgetId);
+  std::string getCreatedBy();
+  void setCreatedBy(std::string createdBy);
+  std::string hash() override;
+  std::string serialize() override;
+  static Transaction deserialize(std::string data);
 };
 #endif
diff --git a/include/twigs/transaction_repository.h b/include/twigs/transaction_repository.h
new file mode 100644
index 0000000..cfeeca6
--- /dev/null
+++ b/include/twigs/transaction_repository.h
@@ -0,0 +1,13 @@
+#define TRANSACTION_REPOSITORY_H
+#ifndef TRANSACTION_REPOSITORY_H
+#include "transaction.h"
+
+class TransactionRepository {
+public:
+  Transaction findById(std::string id);
+  Transaction *findAll(std::string *budgetIds, std::string *categoryIds,
+                       std::string *from, std::string *to, int count, int page);
+  Transaction save(Transaction transaction);
+  void remove(Transaction transaction);
+};
+#endif
diff --git a/include/twigs/user.h b/include/twigs/user.h
index 511db5c..93f2db2 100644
--- a/include/twigs/user.h
+++ b/include/twigs/user.h
@@ -5,11 +5,13 @@
 
 class User: public Identifiable {
     private:
+        std::string id;
         std::string name;
         std::string email;
         std::string avatar;
 
     public:
+        std::string getId() override;
         std::string getName();
         void setName(std::string name);
         std::string getEmail();
diff --git a/include/twigs/utils.h b/include/twigs/utils.h
new file mode 100644
index 0000000..63554ff
--- /dev/null
+++ b/include/twigs/utils.h
@@ -0,0 +1,12 @@
+#ifndef UTILS_H
+#define UTILS_H
+#include <string>
+
+namespace util {
+std::string randomId();
+std::string hash(std::string data);
+tm parseDate(std::string str);
+std::string printDate(tm date);
+} // namespace util
+
+#endif
diff --git a/scripts/build-android b/scripts/build-android
new file mode 100755
index 0000000..a764416
--- /dev/null
+++ b/scripts/build-android
@@ -0,0 +1,198 @@
+#!/usr/bin/env bash
+
+# Configure the following variables according to your needs
+
+NDK_VERSION="21.3.6528147"
+OPENSSL_TAG_VERSION="OpenSSL_1_1_1g "
+CURL_TAG_VERSION="master "
+JSONCPP_TAG_VERSION="master"
+ANDROID_ARCHS="arm arm64 x86 x86_64"
+NDK=$HOME/Android/Sdk/ndk/$NDK_VERSION
+MIN_SDK_VERSION=23 # Can't go any lower unfortunately. See the cURL docs for more info.
+TARGET_SDK_VERSION=29
+
+# Edit below at your own risk
+
+get_abi() {
+    case $1 in
+        "arm")
+            echo -n "armeabi-v7a"
+            ;;
+        "arm64")
+            echo -n "arm64-v8a"
+            ;;
+        "x86")
+            echo -n "x86"
+            ;;
+        "x86_64")
+            echo -n "x86_64"
+            ;;
+    esac
+}
+
+make_openssl() {
+    (
+    cd deps
+    test -d openssl || git clone --branch $OPENSSL_TAG_VERSION https://github.com/openssl/openssl.git
+    for ARCH in $ANDROID_ARCHS; do
+        (
+        export PREFIX="$BUILD_DIR/android/$ARCH"
+        mkdir -p "$PREFIX"
+        cd openssl
+        git checkout $OPENSSL_TAG_VERSION
+        make clean
+        export ANDROID_NDK_HOME=$NDK
+        export ANDROID_NDK_ROOT=$NDK
+        export PATH=$ANDROID_NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin:$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin:$PATH
+        ./Configure \
+            --prefix="$PREFIX" \
+            -D__ANDROID_API__=$TARGET_SDK_VERSION \
+            no-shared \
+            android-$ARCH
+        make install_dev
+        )
+    done
+    )
+}
+
+make_curl() {
+    (
+    cd deps
+    test -d curl || git clone --branch $CURL_TAG_VERSION https://github.com/curl/curl.git
+    for ARCH in $ANDROID_ARCHS; do
+        (
+        export PREFIX="$BUILD_DIR/android/$ARCH"
+        mkdir -p "$PREFIX"
+        cd curl
+        git checkout $CURL_TAG_VERSION
+        test -f configure || ./buildconf
+        export HOST_TAG=linux-x86_64
+        export TOOLCHAIN=$NDK/toolchains/llvm/prebuilt/$HOST_TAG
+        case $ARCH in
+            "arm")
+                export CURL_ARCH="arm-linux-androideabi"
+                export CLANG="armv7a-linux-androideabi"
+                ;;
+            "arm64")
+                export CURL_ARCH="aarch64-linux-android"
+                export CLANG=$CURL_ARCH
+                ;;
+            "x86")
+                export CURL_ARCH="i686-linux-android"
+                export CLANG=$CURL_ARCH
+                ;;
+            "x86_64")
+                export CURL_ARCH="x86_64-linux-android"
+                export CLANG=$CURL_ARCH
+                ;;
+        esac
+        export     AR=$TOOLCHAIN/bin/$CURL_ARCH-ar
+        export     AS=$TOOLCHAIN/bin/$CURL_ARCH-as
+        export     CC=$TOOLCHAIN/bin/${CLANG}${MIN_SDK_VERSION}-clang
+        export    CXX=$TOOLCHAIN/bin/${CLANG}${MIN_SDK_VERSION}-clang++
+        export     LD=$TOOLCHAIN/bin/$CURL_ARCH-ld
+        export RANLIB=$TOOLCHAIN/bin/$CURL_ARCH-ranlib
+        export  STRIP=$TOOLCHAIN/bin/$CURL_ARCH-strip
+        make clean
+        ./configure --prefix="$PREFIX" \
+            --host $CURL_ARCH \
+            --with-pic \
+            --disable-shared \
+            --with-ssl="$PREFIX"
+        make install
+        )
+    done
+    )
+}
+
+make_jsoncpp() {
+    (
+    cd deps
+    test -d jsoncpp || git clone --branch $JSONCPP_TAG_VERSION https://github.com/open-source-parsers/jsoncpp
+    for ARCH in $ANDROID_ARCHS; do
+        (
+        export PREFIX="$BUILD_DIR/android/$ARCH"
+        mkdir -p "$PREFIX"
+        cd jsoncpp
+        git checkout $JSONCPP_TAG_VERSION
+        test -d $ARCH && rm -rf $ARCH
+        mkdir $ARCH
+        pushd $ARCH
+        export ABI="$(get_abi $ARCH)"
+        #TODO: CMake is deprecated, this should use meson/ninja
+        cmake \
+            -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
+            -DANDROID_ABI=$ABI \
+            -DANDROID_NATIVE_API_LEVEL=$MIN_SDK_VERSION \
+            -DCMAKE_INSTALL_PREFIX=$PREFIX \
+            -DBUILD_OBJECT_LIBS=OFF \
+            -DBUILD_SHARED_LIBS=OFF \
+            -DJSONCPP_WITH_TESTS=OFF \
+            -DBUILD_STATIC_LIBS=ON \
+            ..
+            make
+            make install
+        )
+    done
+    )
+}
+
+make_twigs() {
+    (
+    for ARCH in $ANDROID_ARCHS; do
+        (
+        export PREFIX="$BUILD_DIR/android/$ARCH"
+        export ABI="$(get_abi $ARCH)"
+        mkdir -p "$PREFIX"
+        cd "$BUILD_DIR"
+        test -d $ARCH && rm -rf $ARCH
+        mkdir $ARCH
+        pushd $ARCH
+        cmake \
+            -DCMAKE_FIND_ROOT_PATH=$PREFIX \
+            -DCMAKE_INCLUDE_PATH=$PREFIX/include \
+            -DCMAKE_PREFIX_PATH=$PREFIX \
+            -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
+            -DANDROID_ABI=$ABI \
+            -DANDROID_NATIVE_API_LEVEL=$MIN_SDK_VERSION \
+            -DCMAKE_INSTALL_PREFIX=$PREFIX \
+            -DBUILD_SHARED_LIBS=OFF \
+            -DBUILD_TESTING=OFF \
+            -DBUILD_STATIC_LIBS=ON \
+            ../..
+            make
+            make install
+        )
+    done
+    )
+}
+
+package() {
+    for ARCH in $ANDROID_ARCHS; do
+        (
+        export ABI="$(get_abi $ARCH)"
+        cd $BUILD_DIR/android
+        cp -r $ARCH/include .
+        mv $ARCH/lib/*.a $ARCH/lib/*.la $ARCH/
+        rm -rf $ARCH/{bin,lib,include,share}
+        if [ "$ARCH" != "$ABI" ]; then
+            mv $ARCH $ABI
+        fi
+        )
+    done
+}
+
+(
+if [ "$(dirname $0)" == "." ]; then
+    cd ..
+fi
+test -d deps || mkdir deps
+export BUILD_DIR="$PWD/build"
+test -d "$BUILD_DIR" || mkdir -p "$BUILD_DIR"
+make_openssl
+make_curl
+make_jsoncpp
+make_twigs
+package
+)
+
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index e2f3330..7f76d93 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,7 +1,7 @@
 add_subdirectory(libtwigs)
 
-option(TWIGS_TESTS "Build tests for Twigs" ON)
+option(BUILD_TESTING "Build tests for Twigs" ON)
 
-if (TWIGS_TESTS)
+if (BUILD_TESTING)
     add_subdirectory(test)
 endif()
diff --git a/src/libtwigs/CMakeLists.txt b/src/libtwigs/CMakeLists.txt
index 286a54b..a66f1ec 100644
--- a/src/libtwigs/CMakeLists.txt
+++ b/src/libtwigs/CMakeLists.txt
@@ -25,28 +25,41 @@ set(PUBLIC_HEADERS
     ${TWIGS_INCLUDE_DIR}/twigs/hashable.h
     ${TWIGS_INCLUDE_DIR}/twigs/identifiable.h
     ${TWIGS_INCLUDE_DIR}/twigs/permission.h
+    ${TWIGS_INCLUDE_DIR}/twigs/serializable.h
     ${TWIGS_INCLUDE_DIR}/twigs/transaction.h
     ${TWIGS_INCLUDE_DIR}/twigs/user.h
+    ${TWIGS_INCLUDE_DIR}/twigs/utils.h
 )
 
 set(TWIGS_SOURCES
     budget.cpp
     #category.cpp
     transaction.cpp
+    utils.cpp
     #twigs.cpp
     #user.cpp
     )
 
-#if (NOT TARGET CURL)
-    #find_library(
-        #CURL
-        #NAMES curl libcurl
-        #PATHS /usr/local/lib /usr/local/lib64 /usr/lib /usr/lib64 /lib
-        #)
-    #if (NOT CURL)
-        #message(SEND_ERROR "Did not find curl")
-    #endif()
-#endif()
+if (NOT TARGET CURL)
+    find_library(
+        CURL
+        NAMES curl libcurl
+        PATHS /usr/local/lib /usr/local/lib64 /usr/lib /usr/lib64 /lib
+        )
+    if (NOT CURL)
+        message(SEND_ERROR "Did not find curl")
+    endif()
+endif()
+if (NOT TARGET JSONCPP)
+    find_library(
+        JSONCPP
+        NAMES jsoncpp libjsoncpp
+        PATHS /usr/local/lib /usr/local/lib64 /usr/lib /usr/lib64 /lib
+        )
+    if (NOT JSONCPP)
+        message(SEND_ERROR "Did not find jsoncpp")
+    endif()
+endif()
 #if (NOT TARGET JSONC)
     #find_library(
         #JSONC
@@ -57,31 +70,28 @@ set(TWIGS_SOURCES
         #message(SEND_ERROR "Did not find json-c")
     #endif()
 #endif()
-#if (NOT TARGET CRYPTO)
-    #find_library(
-        #CRYPTO
-        #NAMES crypto libcrypto
-        #PATHS /usr/local/lib /usr/local/lib64 /usr/lib /usr/lib64 /lib
-        #)
-    #if (NOT CRYPTO)
-        #message(SEND_ERROR "Did not find OpenSSL")
-    #endif()
-#endif()
-#if (NOT TARGET OPENSSL)
-    #find_library(
-        #OPENSSL
-        #NAMES ssl libssl
-        #PATHS /usr/local/lib /usr/local/lib64 /usr/lib /usr/lib64 /lib
-        #)
-    #if (NOT OPENSSL)
-        #message(SEND_ERROR "Did not find OpenSSL")
-    #endif()
-#endif()
+if (NOT TARGET CRYPTO)
+    find_library(
+        CRYPTO
+        NAMES crypto libcrypto
+        PATHS /usr/local/lib /usr/local/lib64 /usr/lib /usr/lib64 /lib
+        )
+    if (NOT CRYPTO)
+        message(SEND_ERROR "Did not find OpenSSL")
+    endif()
+endif()
+if (NOT TARGET OPENSSL)
+    find_library(
+        OPENSSL
+        NAMES ssl libssl
+        PATHS /usr/local/lib /usr/local/lib64 /usr/lib /usr/lib64 /lib
+        )
+    if (NOT OPENSSL)
+        message(SEND_ERROR "Did not find OpenSSL")
+    endif()
+endif()
 
-option(TWIGS_STATIC "Build Twigs as a static library" ON)
-option(TWIGS_SHARED "Build Twigs as a shared library" OFF)
-
-if (TWIGS_STATIC)
+if (BUILD_SHARED_LIBS)
     add_library(libtwigs SHARED
         ${TWIGS_SOURCES}
         ${PUBLIC_HEADERS}
@@ -93,12 +103,20 @@ else()
         )
 endif()
 
-target_include_directories(libtwigs PRIVATE
+target_include_directories(libtwigs PUBLIC
     $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
     $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/${TWIGS_INCLUDE_DIR}>
     $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include/twigs>
+    SYSTEM ${CMAKE_INCLUDE_PATH} 
+    SYSTEM /usr/local/include
 )
 
+target_link_libraries(libtwigs ${JSONCPP}
+    ${CURL}
+    ${CRYPTO}
+    ${OPENSSL}
+    )
+
 set_target_properties(libtwigs PROPERTIES
     OUTPUT_NAME "twigs"
     VERSION ${PROJECT_VERSION}
@@ -106,12 +124,8 @@ set_target_properties(libtwigs PROPERTIES
     )
     
 install(TARGETS libtwigs
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
     ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    OBJECTS DESTINATION ${CMAKE_INSTALL_LIBDIR}
     )
-
-#target_link_libraries(twigs ${CURL}
-    #${JSONC}
-    #${CRYPTO}
-    #${OPENSSL}
-    #)
diff --git a/src/libtwigs/budget.cpp b/src/libtwigs/budget.cpp
index d0f52de..e1568fe 100644
--- a/src/libtwigs/budget.cpp
+++ b/src/libtwigs/budget.cpp
@@ -1,6 +1,51 @@
-#include <twigs/budget.h>
 #include <string>
+#include <twigs/budget.h>
+#include <twigs/utils.h>
+#include <json/json.h>
 
-std::string Budget::hash() {
-    return "";
+Budget::Budget() : Budget(util::randomId(), "", "") {}
+
+Budget::Budget(std::string id, std::string name, std::string description)
+    : id(id), name(name), description(description) {}
+
+std::string Budget::getId() { return this->id; }
+
+string Budget::getName() { return this->name; }
+
+void Budget::setName(string name) { this->name = name; }
+
+string Budget::getDescription() { return this->description; }
+
+void Budget::setDescription(string description) {
+  this->description = description;
 }
+
+std::string Budget::serialize() {
+  Json::Value budget;
+  budget["id"] = this->getId();
+  budget["name"] = this->getName();
+  budget["description"] = this->getDescription();
+  Json::StreamWriterBuilder builder;
+  builder["indentation"] = "";
+  return Json::writeString(builder, budget);
+}
+
+Budget Budget::deserialize(std::string data) {
+  Json::CharReaderBuilder builder;
+  Json::Value root;
+  if (!builder.newCharReader()->parse(&data[0], &data[0] + data.size(), &root,
+                                      NULL)) {
+    // TODO: Log errors
+    //         std::cout << "Failed to create budget from JSON" << "\n";
+    throw 5;
+  }
+  std::string id = root.get("id", "").asString();
+  if (id == "") {
+    throw 5;
+  }
+  std::string name = root.get("name", "").asString();
+  std::string description = root.get("description", "").asString();
+  return Budget(id, name, description);
+}
+
+string Budget::hash() { return util::hash(serialize()); }
diff --git a/src/libtwigs/category.cpp b/src/libtwigs/category.cpp
new file mode 100644
index 0000000..e8a4582
--- /dev/null
+++ b/src/libtwigs/category.cpp
@@ -0,0 +1,76 @@
+#include <twigs/category.h>
+#include <twigs/utils.h>
+
+Category::Category() : Category(util::randomId(), "", "") {}
+
+Category::Category(std::string id, std::string name, std::string budgetId,
+                   std::string description, unsigned int amount, bool expense,
+                   bool archived)
+    : id(id), name(name), budgetId(budgetId), description(description),
+      amount(amount), expense(expense), archived(archived) {}
+
+std::string Category::getId() { return this->id; }
+
+std::string Category::getName() { return this->name; }
+
+void Category::setName(std::string name) { this->name = name; }
+
+std::string Category::getDescription() { return this->description; }
+
+void Category::setDescription(std::string description) {
+  this->description = description;
+}
+
+long Category::getAmount() { return this->amount; }
+
+void Category::setAmount(long amount) { this->amount = amount; }
+
+bool Category::isExpense() { return this->expense; }
+
+void Category::setExpense(bool expense) { this->expense = expense; }
+
+bool Category::isArchived() { return this->archived; }
+
+void Category::setArchived(bool archived) { this->archived = archived; }
+
+std::string Category::getBudgetId() { return this->budgetId; }
+
+void Category::setBudgetId(std::string budgetId) { this->budgetId = budgetId; }
+
+std::string Category::serialize() {
+  Json::Value category;
+  category["id"] = this->getId();
+  category["name"] = this->getName();
+  category["description"] = this->getDescription();
+  category["amount"] = this->getAmount();
+  category["expense"] = this->isExpense();
+  category["archived"] = this->isArchived();
+  category["budgetId"] = this->getBudgetId();
+  Json::StreamWriterBuilder builder;
+  builder["indentation"] = "";
+  return Json::writeString(builder, transaction);
+}
+
+Category Category::deserialize(std::string data) {
+  Json::CharReaderBuilder builder;
+  Json::Value root;
+  if (!builder.newCharReader()->parse(&data[0], &data[0] + data.size(), &root,
+                                      NULL)) {
+    // TODO: Log errors
+    //         std::cout << "Failed to create transaction from JSON" << "\n";
+    throw 5;
+  }
+  std::string id = root.get("id", "").asString();
+  if (id == "") {
+    throw 5;
+  }
+  std::string name = root.get("name", "").asString();
+  std::string description = root.get("description", "").asString();
+  long amount = root.get("amount", 0).asUInt();
+  bool expense = root.get("expense", true).asBool();
+  bool archived = root.get("archived", true).asBool();
+  std::string budgetId = root.get("budgetId", "").asString();
+  return Category(id, name, description);
+}
+
+string Category::hash() { return util::hash(serialize()); }
diff --git a/src/libtwigs/transaction.cpp b/src/libtwigs/transaction.cpp
index 3156602..70d1534 100644
--- a/src/libtwigs/transaction.cpp
+++ b/src/libtwigs/transaction.cpp
@@ -1,8 +1,105 @@
+#include <json/json.h>
+#include <twigs/serializable.h>
 #include <twigs/transaction.h>
+#include <twigs/utils.h>
 
 using namespace std;
 
-string Transaction::hash() {
-    throw 5;
-//     return "";
+tm *now() {
+  time_t now = time(NULL);
+  return gmtime(&now);
 }
+
+Transaction::Transaction() : Transaction(util::randomId(), "", *now(), "") {}
+
+Transaction::Transaction(std::string id, std::string name, tm date,
+                         std::string createdBy, unsigned int amount,
+                         std::string description, bool expense,
+                         std::string categoryId, std::string budgetId)
+    : id(id), name(name), description(description), date(date), amount(amount),
+      expense(expense), categoryId(categoryId), budgetId(budgetId),
+      createdBy(createdBy) {}
+
+string Transaction::getId() { return this->id; }
+
+string Transaction::getName() { return this->name; }
+
+void Transaction::setName(std::string name) { this->name = name; }
+
+string Transaction::getDescription() { return this->description; }
+
+void Transaction::setDescription(string description) {
+  this->description = description;
+}
+
+tm Transaction::getDate() { return this->date; }
+
+void Transaction::setDate(tm date) { this->date = date; }
+
+unsigned int Transaction::getAmount() { return this->amount; }
+
+void Transaction::setAmount(unsigned int amount) { this->amount = amount; }
+
+bool Transaction::isExpense() { return this->expense; }
+
+void Transaction::setExpense(bool expense) { this->expense = expense; }
+
+string Transaction::getCategoryId() { return this->categoryId; }
+
+void Transaction::setCategoryId(string categoryId) {
+  this->categoryId = categoryId;
+}
+
+string Transaction::getBudgetId() { return this->budgetId; }
+
+void Transaction::setBudgetId(string budgetId) { this->budgetId = budgetId; }
+
+string Transaction::getCreatedBy() { return this->createdBy; }
+
+void Transaction::setCreatedBy(string createdBy) {
+  this->createdBy = createdBy;
+}
+
+std::string Transaction::serialize() {
+  Json::Value transaction;
+  transaction["id"] = this->getId();
+  transaction["title"] = this->getName();
+  transaction["description"] = this->getDescription();
+  transaction["date"] = util::printDate(this->getDate());
+  transaction["amount"] = this->getAmount();
+  transaction["expense"] = this->isExpense();
+  transaction["budgetId"] = this->getBudgetId();
+  transaction["categoryId"] = this->getCategoryId();
+  transaction["createdBy"] = this->getCreatedBy();
+  Json::StreamWriterBuilder builder;
+  builder["indentation"] = "";
+  return Json::writeString(builder, transaction);
+}
+
+Transaction Transaction::deserialize(std::string data) {
+  Json::CharReaderBuilder builder;
+  Json::Value root;
+  if (!builder.newCharReader()->parse(&data[0], &data[0] + data.size(), &root,
+                                      NULL)) {
+    // TODO: Log errors
+    //         std::cout << "Failed to create transaction from JSON" << "\n";
+    throw 5;
+  }
+  std::string id = root.get("id", "").asString();
+  if (id == "") {
+    throw 5;
+  }
+  std::string name = root.get("title", "").asString();
+  std::string description = root.get("description", "").asString();
+  std::string dateStr = root.get("date", "").asString();
+  tm date = util::parseDate(dateStr);
+  long amount = root.get("amount", 0).asUInt();
+  bool expense = root.get("expense", true).asBool();
+  std::string budgetId = root.get("budgetId", "").asString();
+  std::string categoryId = root.get("categoryId", "").asString();
+  std::string createdBy = root.get("createdBy", "").asString();
+  return Transaction(id, name, date, createdBy, amount, description, expense,
+                     categoryId, budgetId);
+}
+
+string Transaction::hash() { return util::hash(serialize()); }
diff --git a/src/libtwigs/utils.cpp b/src/libtwigs/utils.cpp
new file mode 100644
index 0000000..d0feed7
--- /dev/null
+++ b/src/libtwigs/utils.cpp
@@ -0,0 +1,61 @@
+#include <random>
+#include <twigs/utils.h>
+#include <openssl/sha.h>
+
+namespace util {
+std::string randomId() {
+  const std::string CHARACTERS =
+      "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+  const int ID_LEN = 32;
+
+  std::random_device rd;
+  std::mt19937 engine(rd());
+  std::uniform_int_distribution<> distribution(0, CHARACTERS.size() - 1);
+
+  std::string random_string;
+
+  for (std::size_t i = 0; i < ID_LEN; ++i) {
+    random_string += CHARACTERS[distribution(engine)];
+  }
+
+  return random_string;
+}
+
+tm parseDate(std::string str) {
+  static tm date;
+  // TODO: Handle exceptions
+  int year = stoi(str.substr(0, 4));
+  int mon = stoi(str.substr(5, 2));
+  int day = stoi(str.substr(8, 2));
+  int hours = stoi(str.substr(11, 2));
+  int min = stoi(str.substr(14, 2));
+  int sec = stoi(str.substr(17, 2));
+  date.tm_year = year;
+  date.tm_mon = mon - 1;
+  date.tm_mday = day;
+  date.tm_hour = hours;
+  date.tm_min = min;
+  date.tm_sec = sec;
+  return date;
+}
+
+std::string printDate(tm date) {
+  static char str[25];
+  snprintf(str, 21, "%04d-%02d-%02dT%02d:%02d:%02dZ", date.tm_year,
+           date.tm_mon + 1, date.tm_mday, date.tm_hour, date.tm_min,
+           date.tm_sec);
+  return str;
+}
+
+std::string hash(std::string data) {
+    unsigned char bytes[SHA256_DIGEST_LENGTH];
+    SHA256((unsigned char *) &data[0], data.size(), bytes);
+    char hash[(SHA256_DIGEST_LENGTH * 2) + 1];
+    int i;
+    for(i = 0; i < SHA256_DIGEST_LENGTH; i++) {
+        sprintf(hash + (i * 2), "%02x", bytes[i]);
+    }
+    hash[SHA256_DIGEST_LENGTH * 2] = '\0';
+    return std::string(hash, SHA256_DIGEST_LENGTH * 2);
+}
+} // namespace util
diff --git a/src/test/CMakeLists.txt b/src/test/CMakeLists.txt
index 7de2ddd..8d0620d 100644
--- a/src/test/CMakeLists.txt
+++ b/src/test/CMakeLists.txt
@@ -6,29 +6,27 @@ set(TEST_SOURCES
     budget_test.cpp
     transaction_test.h
     transaction_test.cpp
+    utils_test.h
+    utils_test.cpp
 )
 
 find_library(CPPUNIT cppunit)
     
-add_executable(twigs_test
-    ${TEST_SOURCES}
-    ${PUBLIC_HEADERS}
-)
+add_executable(twigs_test ${TEST_SOURCES})
     
 target_link_libraries(twigs_test libtwigs ${CPPUNIT})
-    
-target_include_directories(twigs_test PRIVATE
-    $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
-    $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/${TWIGS_INCLUDE_DIR}>
-    $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include/twigs>
-)
-
-message("CMAKE_INSTALL_INCLUDEDIR: ${CMAKE_INSTALL_INCLUDEDIR}")
-message("CMAKE_CURRENT_LIST_DIR}/TWIGS_INCLUDE_DIR ${CMAKE_CURRENT_LIST_DIR}/${TWIGS_INCLUDE_DIR}")
-message("PROJECT_BINARY_DIR/include/twigs: ${PROJECT_BINARY_DIR}/include/twigs}")
-
+        
 set_target_properties(twigs_test PROPERTIES
     OUTPUT_NAME "twigstest"
     VERSION ${PROJECT_VERSION}
     SOVERSION ${PROJECT_VERSION_MAJOR}
     )
+
+add_test(NAME twigs_test
+    COMMAND ${CMAKE_CROSSCOMPILING_EMULATOR} $<TARGET_FILE:twigs_test>
+)
+
+add_custom_command(TARGET twigs_test
+    POST_BUILD
+    COMMAND ${CMAKE_CROSSCOMPILING_EMULATOR} $<TARGET_FILE:twigs_test>
+    )
diff --git a/src/test/budget_test.cpp b/src/test/budget_test.cpp
index 4849c6b..50e6932 100644
--- a/src/test/budget_test.cpp
+++ b/src/test/budget_test.cpp
@@ -1,6 +1,41 @@
-#include <cppunit/extensions/HelperMacros.h>
 #include "budget_test.h"
+#include <cppunit/extensions/HelperMacros.h>
 
-void BudgetTest::parseDate() {
-    Budget budget;
+void BudgetTest::serialize() {
+  const std::string json =
+      R"({"description":"Monthly expenses","id":"Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU","name":"Monthly Budget"})";
+  Budget b = Budget("Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU", "Monthly Budget",
+                    "Monthly expenses");
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Budget serialization failed", json,
+                               b.serialize());
+}
+
+void BudgetTest::deserialize() {
+  const std::string json =
+      R"({"description":"Monthly expenses","id":"Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU","name":"Monthly Budget"})";
+  Budget b = Budget::deserialize(json);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Budget id parsing failed",
+                               std::string("Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU"),
+                               b.getId());
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Budget name parsing failed",
+                               std::string("Monthly Budget"), b.getName());
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Budget description parsing failed",
+                               std::string("Monthly expenses"),
+                               b.getDescription());
+}
+
+void BudgetTest::defaultIdsDifferent() {
+  Budget b1;
+  Budget b2;
+  CPPUNIT_ASSERT(b1.getId() != b2.getId());
+}
+
+void BudgetTest::hashBudget() {
+  Budget b = Budget("Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU", "Monthly Budget",
+                    "Monthly expenses");
+  CPPUNIT_ASSERT_EQUAL_MESSAGE(
+      "Budget hash failed",
+      std::string(
+          "12fd354740ec016a4b50e2edd1e586107784fe7b88001d8d6ab7ba9ce38aa1d6"),
+      b.hash());
 }
diff --git a/src/test/budget_test.h b/src/test/budget_test.h
index d2d8141..62e14de 100644
--- a/src/test/budget_test.h
+++ b/src/test/budget_test.h
@@ -7,10 +7,16 @@
 
 class BudgetTest: public CppUnit::TestCase {
 public:
-    void parseDate();
-    
+    void serialize();
+    void deserialize();
+    void defaultIdsDifferent();
+    void hashBudget();
+
     CPPUNIT_TEST_SUITE( BudgetTest );
-    CPPUNIT_TEST( parseDate );
+    CPPUNIT_TEST( serialize );
+    CPPUNIT_TEST( deserialize );
+    CPPUNIT_TEST( defaultIdsDifferent );
+    CPPUNIT_TEST( hashBudget );
     CPPUNIT_TEST_SUITE_END();
 };
 
diff --git a/src/test/main.cpp b/src/test/main.cpp
index ed97c2a..1a0d2fe 100644
--- a/src/test/main.cpp
+++ b/src/test/main.cpp
@@ -1,12 +1,16 @@
 #include <cppunit/TextTestRunner.h>
 #include "budget_test.h"
 #include "transaction_test.h"
+#include "utils_test.h"
 
+CPPUNIT_TEST_SUITE_REGISTRATION (UtilsTest);
+CPPUNIT_TEST_SUITE_REGISTRATION (BudgetTest);
 CPPUNIT_TEST_SUITE_REGISTRATION (TransactionTest);
 
 int main() {
     BudgetTest budgetTest;
     TransactionTest transactionTest;
+    UtilsTest utilsTest;
     
     CppUnit::Test *test = CppUnit::TestFactoryRegistry::getRegistry().makeTest();
     CppUnit::TextTestRunner runner;
diff --git a/src/test/transaction_test.cpp b/src/test/transaction_test.cpp
index 22e59cd..0625834 100644
--- a/src/test/transaction_test.cpp
+++ b/src/test/transaction_test.cpp
@@ -1,9 +1,84 @@
+#include "transaction_test.h"
 #include <cppunit/TestCase.h>
 #include <cppunit/extensions/HelperMacros.h>
-#include "transaction_test.h"
+#include <iostream>
+#include <time.h>
+#include <twigs/utils.h>
 
-void TransactionTest::parseDate() {
-    Transaction transaction;
-    transaction.setDate("2020-01-31T23:59:59Z");
-    CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction date parsing failed", std::string("2020-01-31T23:59:59Z"), transaction.getDate());
+void TransactionTest::serialize() {
+  const std::string json =
+      R"({"amount":2108,"budgetId":"Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU","categoryId":"Q4R8QLhSksL2wi7XzmrqhL06qm2aZ2S4","createdBy":"1","date":"2021-01-08T13:06:00Z","description":"Books","expense":true,"id":"2snbSS8flrSH6OrvmSEmqyvaduOi2uc2","title":"Amazon"})";
+
+  tm date;
+  date.tm_year = 2021;
+  date.tm_mon = 0;
+  date.tm_mday = 8;
+  date.tm_hour = 13;
+  date.tm_min = 6;
+  date.tm_sec = 0;
+  Transaction t =
+      Transaction("2snbSS8flrSH6OrvmSEmqyvaduOi2uc2", "Amazon", date, "1", 2108,
+                  "Books", true, "Q4R8QLhSksL2wi7XzmrqhL06qm2aZ2S4",
+                  "Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU");
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction serialization failed", json,
+                               t.serialize());
+}
+
+void TransactionTest::deserialize() {
+  const std::string json =
+      R"({"id":"2snbSS8flrSH6OrvmSEmqyvaduOi2uc2","title":"Amazon","description":"Books","date":"2021-01-08T13:06:00Z","amount":2108,"expense":true,"budgetId":"Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU","categoryId":"Q4R8QLhSksL2wi7XzmrqhL06qm2aZ2S4","createdBy":"1"})";
+  Transaction t = Transaction::deserialize(json);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction id parsing failed",
+                               std::string("2snbSS8flrSH6OrvmSEmqyvaduOi2uc2"),
+                               t.getId());
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction name parsing failed",
+                               std::string("Amazon"), t.getName());
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction description parsing failed",
+                               std::string("Books"), t.getDescription());
+  tm date = t.getDate();
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction date year parsing failed", 2021,
+                               date.tm_year);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction date month parsing failed", 0,
+                               date.tm_mon);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction date day parsing failed", 8,
+                               date.tm_mday);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction date hour parsing failed", 13,
+                               date.tm_hour);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction date min parsing failed", 6,
+                               date.tm_min);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction date sec parsing failed", 0,
+                               date.tm_sec);
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction amount parsing failed", 2108U,
+                               t.getAmount());
+  CPPUNIT_ASSERT_MESSAGE("Transaction expense parsing failed", t.isExpense());
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction budgetId parsing failed",
+                               std::string("Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU"),
+                               t.getBudgetId());
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction category parsing failed",
+                               std::string("Q4R8QLhSksL2wi7XzmrqhL06qm2aZ2S4"),
+                               t.getCategoryId());
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction createdBy parsing failed",
+                               std::string("1"), t.getCreatedBy());
+}
+
+void TransactionTest::defaultIdsDifferent() {
+  Transaction t1;
+  Transaction t2;
+  CPPUNIT_ASSERT(t1.getId() != t2.getId());
+}
+
+void TransactionTest::hashTransaction() {
+  tm date;
+  date.tm_year = 2021;
+  date.tm_mon = 0;
+  date.tm_mday = 8;
+  date.tm_hour = 13;
+  date.tm_min = 6;
+  date.tm_sec = 0;
+  Transaction t =
+      Transaction("2snbSS8flrSH6OrvmSEmqyvaduOi2uc2", "Amazon", date, "1", 2108,
+                  "Books", true, "Q4R8QLhSksL2wi7XzmrqhL06qm2aZ2S4",
+                  "Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU");
+      CPPUNIT_ASSERT_EQUAL_MESSAGE("Transaction hash failed",
+                               std::string("94140eb2923e905360cef1e7aca3d321da39f0608ea17eb944475d81b89a64cb"), t.hash());
 }
diff --git a/src/test/transaction_test.h b/src/test/transaction_test.h
index b23f4d3..5c6e35b 100644
--- a/src/test/transaction_test.h
+++ b/src/test/transaction_test.h
@@ -7,10 +7,16 @@
 
 class TransactionTest: public CppUnit::TestCase {
 public:
-    void parseDate();
+    void serialize();
+    void deserialize();
+    void defaultIdsDifferent();
+    void hashTransaction();
     
     CPPUNIT_TEST_SUITE( TransactionTest );
-    CPPUNIT_TEST( parseDate );
+    CPPUNIT_TEST( serialize );
+    CPPUNIT_TEST( deserialize );
+    CPPUNIT_TEST( defaultIdsDifferent );
+    CPPUNIT_TEST( hashTransaction );
     CPPUNIT_TEST_SUITE_END();
 };
 
diff --git a/src/test/utils_test.cpp b/src/test/utils_test.cpp
new file mode 100644
index 0000000..0deab0b
--- /dev/null
+++ b/src/test/utils_test.cpp
@@ -0,0 +1,24 @@
+#include "utils_test.h"
+#include <cppunit/TestCase.h>
+#include <cppunit/extensions/HelperMacros.h>
+
+void UtilsTest::parseDateTest() {}
+
+void UtilsTest::printDateTest() {
+  tm date;
+  date.tm_year = 2020;
+  date.tm_mon = 0;
+  date.tm_mday = 31;
+  date.tm_hour = 23;
+  date.tm_min = 59;
+  date.tm_sec = 59;
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Date printing failed",
+                               std::string("2020-01-31T23:59:59Z"),
+                               util::printDate(date));
+}
+
+void UtilsTest::hashTest() { 
+  CPPUNIT_ASSERT_EQUAL_MESSAGE("Hashing failed",
+                               std::string("9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"),
+                               util::hash("test"));
+}
diff --git a/src/test/utils_test.h b/src/test/utils_test.h
new file mode 100644
index 0000000..1962048
--- /dev/null
+++ b/src/test/utils_test.h
@@ -0,0 +1,21 @@
+#ifndef UTILS_TEST_H_INCLUDED
+#define UTILS_TEST_H_INCLUDED
+
+#include <cppunit/TestCase.h>
+#include <cppunit/extensions/HelperMacros.h>
+#include <twigs/utils.h>
+
+class UtilsTest: public CppUnit::TestCase {
+public:
+    void parseDateTest();
+    void printDateTest();
+    void hashTest();
+    
+    CPPUNIT_TEST_SUITE( UtilsTest );
+    CPPUNIT_TEST( parseDateTest );
+    CPPUNIT_TEST( printDateTest );
+    CPPUNIT_TEST( hashTest );
+    CPPUNIT_TEST_SUITE_END();
+};
+
+#endif // UTILS_TEST_H_INCLUDED
diff --git a/transaction.json b/transaction.json
new file mode 100644
index 0000000..8eb9b8c
--- /dev/null
+++ b/transaction.json
@@ -0,0 +1 @@
+{"amount":2108,"budgetId":"Gbhqm79yC8NereIONtq7W2Mf9MD2y1AU","categoryId":"Q4R8QLhSksL2wi7XzmrqhL06qm2aZ2S4","createdBy":"1","date":"2021-01-08T13:06:00Z","description":"Books","expense":true,"id":"2snbSS8flrSH6OrvmSEmqyvaduOi2uc2","title":"Amazon"}