diff --git a/model/app.go b/model/app.go
index 89d656d..7abc8ec 100644
--- a/model/app.go
+++ b/model/app.go
@@ -2,7 +2,6 @@ package model
 
 import (
 	"errors"
-	"strings"
 )
 
 var (
@@ -10,31 +9,13 @@ var (
 )
 
 type App struct {
-	InstanceDomain string
-	InstanceURL    string
-	ClientID       string
-	ClientSecret   string
+	InstanceDomain string `json:"instance_domain"`
+	InstanceURL    string `json:"instance_url"`
+	ClientID       string `json:"client_id"`
+	ClientSecret   string `json:"client_secret"`
 }
 
 type AppRepository interface {
 	Add(app App) (err error)
 	Get(instanceDomain string) (app App, err error)
 }
-
-func (a *App) Marshal() []byte {
-	str := a.InstanceURL + "\n" + a.ClientID + "\n" + a.ClientSecret
-	return []byte(str)
-}
-
-func (a *App) Unmarshal(instanceDomain string, data []byte) error {
-	str := string(data)
-	lines := strings.Split(str, "\n")
-	if len(lines) != 3 {
-		return errors.New("invalid data")
-	}
-	a.InstanceDomain = instanceDomain
-	a.InstanceURL = lines[0]
-	a.ClientID = lines[1]
-	a.ClientSecret = lines[2]
-	return nil
-}
diff --git a/model/session.go b/model/session.go
index 94f527b..af9e9e2 100644
--- a/model/session.go
+++ b/model/session.go
@@ -2,7 +2,6 @@ package model
 
 import (
 	"errors"
-	"strings"
 )
 
 var (
@@ -10,9 +9,9 @@ var (
 )
 
 type Session struct {
-	ID             string
-	InstanceDomain string
-	AccessToken    string
+	ID             string `json:"id"`
+	InstanceDomain string `json:"instance_domain"`
+	AccessToken    string `json:"access_token"`
 }
 
 type SessionRepository interface {
@@ -24,26 +23,3 @@ type SessionRepository interface {
 func (s Session) IsLoggedIn() bool {
 	return len(s.AccessToken) > 0
 }
-
-func (s *Session) Marshal() []byte {
-	str := s.InstanceDomain + "\n" + s.AccessToken
-	return []byte(str)
-}
-
-func (s *Session) Unmarshal(id string, data []byte) error {
-	str := string(data)
-	lines := strings.Split(str, "\n")
-
-	size := len(lines)
-	if size == 1 {
-		s.InstanceDomain = lines[0]
-	} else if size == 2 {
-		s.InstanceDomain = lines[0]
-		s.AccessToken = lines[1]
-	} else {
-		return errors.New("invalid data")
-	}
-
-	s.ID = id
-	return nil
-}
diff --git a/repository/appRepository.go b/repository/appRepository.go
index 00ef64d..cfa7950 100644
--- a/repository/appRepository.go
+++ b/repository/appRepository.go
@@ -1,6 +1,7 @@
 package repository
 
 import (
+	"encoding/json"
 	"web/kv"
 	"web/model"
 )
@@ -16,7 +17,11 @@ func NewAppRepository(db *kv.Database) *appRepository {
 }
 
 func (repo *appRepository) Add(a model.App) (err error) {
-	err = repo.db.Set(a.InstanceDomain, a.Marshal())
+	data, err := json.Marshal(a)
+	if err != nil {
+		return
+	}
+	err = repo.db.Set(a.InstanceDomain, data)
 	return
 }
 
@@ -27,7 +32,10 @@ func (repo *appRepository) Get(instanceDomain string) (a model.App, err error) {
 		return
 	}
 
-	err = a.Unmarshal(instanceDomain, data)
+	err = json.Unmarshal(data, &a)
+	if err != nil {
+		return
+	}
 
 	return
 }
diff --git a/repository/sessionRepository.go b/repository/sessionRepository.go
index 6c26313..d5f399a 100644
--- a/repository/sessionRepository.go
+++ b/repository/sessionRepository.go
@@ -1,6 +1,7 @@
 package repository
 
 import (
+	"encoding/json"
 	"web/kv"
 	"web/model"
 )
@@ -16,7 +17,11 @@ func NewSessionRepository(db *kv.Database) *sessionRepository {
 }
 
 func (repo *sessionRepository) Add(s model.Session) (err error) {
-	err = repo.db.Set(s.ID, s.Marshal())
+	data, err := json.Marshal(s)
+	if err != nil {
+		return
+	}
+	err = repo.db.Set(s.ID, data)
 	return
 }
 
@@ -27,14 +32,19 @@ func (repo *sessionRepository) Update(id string, accessToken string) (err error)
 	}
 
 	var s model.Session
-	err = s.Unmarshal(id, data)
+	err = json.Unmarshal(data, &s)
 	if err != nil {
 		return
 	}
 
 	s.AccessToken = accessToken
 
-	return repo.db.Set(id, s.Marshal())
+	data, err = json.Marshal(s)
+	if err != nil {
+		return
+	}
+
+	return repo.db.Set(id, data)
 }
 
 func (repo *sessionRepository) Get(id string) (s model.Session, err error) {
@@ -44,7 +54,10 @@ func (repo *sessionRepository) Get(id string) (s model.Session, err error) {
 		return
 	}
 
-	err = s.Unmarshal(id, data)
+	err = json.Unmarshal(data, &s)
+	if err != nil {
+		return
+	}
 
 	return
 }