diff --git a/cmd/aggregate.go b/cmd/aggregate.go
index 03d7010..958b8bf 100644
--- a/cmd/aggregate.go
+++ b/cmd/aggregate.go
@@ -1,9 +1,12 @@
 package cmd
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 
+	"github.com/mamezou-tech/sbgraph/pkg/file"
+
 	"github.com/cheggaaa/pb/v3"
 	"github.com/mamezou-tech/sbgraph/pkg/types"
 	"github.com/spf13/cobra"
@@ -18,7 +21,8 @@ var aggregateCmd = &cobra.Command{
 
 	  sbf aggregate
 
-	CSV will be created at '<WorkDir>/<project name>.csv'.
+	JSON will be created as '<WorkDir>/<project name>_ag.json'.
+	If the csv flag is specified, CSV will be created as '<WorkDir>/project name>_ag.csv'.
 	`),
 	Run: func(cmd *cobra.Command, args []string) {
 		doAggregate(cmd)
@@ -26,26 +30,19 @@ var aggregateCmd = &cobra.Command{
 }
 
 func init() {
+	aggregateCmd.PersistentFlags().BoolP("csv", "s", false, "Output as CSV")
 	rootCmd.AddCommand(aggregateCmd)
 }
 
-type contribute struct {
-	UserID            string
-	UserName          string
-	PagesCreated      int
-	PagesContributed  int
-	ViewsCreatedPages int
-	LinksCreatedPages int
-}
-
 func doAggregate(cmd *cobra.Command) {
+	csv, _ := cmd.PersistentFlags().GetBool("csv")
 	projectName := config.CurrentProject
 	CheckProject(projectName)
 	fmt.Printf("Aggregate project : %s\n", projectName)
 	var proj types.Project
 	err := proj.ReadFrom(projectName, config.WorkDir)
 	CheckErr(err)
-	contrib := map[string]contribute{}
+	contrib := map[string]types.Contribution{}
 	bar := pb.StartNew(proj.Count)
 	for _, idx := range proj.Pages {
 		var page types.Page
@@ -58,7 +55,7 @@ func doAggregate(cmd *cobra.Command) {
 			p.LinksCreatedPages += page.Linked
 			contrib[page.Author.ID] = p
 		} else {
-			c := contribute{
+			c := types.Contribution{
 				UserID:            page.Author.ID,
 				UserName:          page.Author.DisplayName,
 				PagesContributed:  1,
@@ -73,7 +70,7 @@ func doAggregate(cmd *cobra.Command) {
 				p.PagesContributed++
 				contrib[user.ID] = p
 			} else {
-				c := contribute{
+				c := types.Contribution{
 					UserID:           user.ID,
 					UserName:         user.DisplayName,
 					PagesContributed: 1,
@@ -84,24 +81,32 @@ func doAggregate(cmd *cobra.Command) {
 		bar.Increment()
 	}
 	bar.Finish()
-	err = writeContrib(projectName, contrib)
+	err = writeContrib(projectName, contrib, csv)
 	CheckErr(err)
 }
 
-func writeContrib(projectName string, contrib map[string]contribute) error {
-	path := fmt.Sprintf("%s/%s.csv", config.WorkDir, projectName)
-	file, err := os.Create(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-	file.Write(([]byte)("User Name,Pages Created,Pages Contributed,Views of Created Pages,Links of Created Pages\n"))
-	for _, v := range contrib {
-		data := fmt.Sprintf("%s,%d,%d,%d,%d\n", v.UserName, v.PagesCreated, v.PagesContributed, v.ViewsCreatedPages, v.LinksCreatedPages)
-		_, err = file.Write(([]byte)(data))
+func writeContrib(projectName string, contrib map[string]types.Contribution, csv bool) error {
+	if csv {
+		path := fmt.Sprintf("%s/%s_contrib.csv", config.WorkDir, projectName)
+		fmt.Println(path)
+		file, err := os.Create(path)
 		if err != nil {
 			return err
 		}
+		defer file.Close()
+		file.Write(([]byte)("User ID, User Name,Pages Created,Pages Contributed,Views of Created Pages,Links of Created Pages\n"))
+		for _, v := range contrib {
+			data := fmt.Sprintf("%s,%s,%d,%d,%d,%d\n", v.UserID, v.UserName, v.PagesCreated, v.PagesContributed, v.ViewsCreatedPages, v.LinksCreatedPages)
+			_, err = file.Write(([]byte)(data))
+			if err != nil {
+				return err
+			}
+		}
+	} else {
+		data, _ := json.Marshal(contrib)
+		if err := file.WriteBytes(data, projectName+"_contrib.json", config.WorkDir); err != nil {
+			return err
+		}
 	}
 	return nil
 }
diff --git a/cmd/fetch.go b/cmd/fetch.go
index 24b417f..28cfc83 100644
--- a/cmd/fetch.go
+++ b/cmd/fetch.go
@@ -3,6 +3,7 @@ package cmd
 import (
 	"encoding/json"
 	"fmt"
+	"os"
 	"sync"
 	"time"
 
@@ -107,6 +108,17 @@ func fetchPageList(project types.Project) error {
 			pages = append(pages, page)
 		}
 	}
+	contrib, err := readContrib()
+	if err != nil {
+		return err
+	}
+	for idx, page := range pages {
+		u, contains := contrib[page.Author.ID]
+		if contains {
+			pages[idx].Author.Name = u.UserName
+			pages[idx].Author.DisplayName = u.UserName
+		}
+	}
 	project.Pages = pages
 	jst, _ := time.LoadLocation("Asia/Tokyo")
 	project.Date = time.Now().In(jst).Format(timeLayout)
@@ -117,6 +129,19 @@ func fetchPageList(project types.Project) error {
 	return nil
 }
 
+func readContrib() (map[string]types.Contribution, error) {
+	contrib := map[string]types.Contribution{}
+	bytes, err := file.ReadBytes(config.CurrentProject+"_contrib.json", config.WorkDir)
+	if os.IsNotExist(err) {
+		return contrib, nil
+	}
+	if err != nil {
+		return contrib, err
+	}
+	err = json.Unmarshal(bytes, &contrib)
+	return contrib, err
+}
+
 func dividePagesList(multiplicity int, projectName string) ([][]types.Page, error) {
 	var divided [][]types.Page
 	var proj types.Project
diff --git a/pkg/types/page.go b/pkg/types/page.go
index 1c25427..1073d2c 100644
--- a/pkg/types/page.go
+++ b/pkg/types/page.go
@@ -34,6 +34,16 @@ type User struct {
 	PagesCreated []string
 }
 
+// Contribution represents summary of the user's contribution
+type Contribution struct {
+	UserID            string `json:"userId"`
+	UserName          string `json:"userName"`
+	PagesCreated      int    `json:"pagesCreated"`
+	PagesContributed  int    `json:"pagesContributed"`
+	ViewsCreatedPages int    `json:"viewsCreatedPages"`
+	LinksCreatedPages int    `json:"linksCreatedPages"`
+}
+
 // ReadFrom will deserialize Project from file
 func (page *Page) ReadFrom(projectName string, id string, workDir string) error {
 	bytes, err := file.ReadBytes(id+".json", workDir+"/"+projectName)