diff --git a/internal/config/config.go b/internal/config/config.go
index b36c319e7..f377a8374 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -2,6 +2,9 @@ package config
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"runtime"
 	"strings"
 	"sync"
@@ -33,6 +36,7 @@ type Config struct {
 	settings *Settings
 	hub      *hub.Config
 	token    string
+	serial   string
 }
 
 func init() {
@@ -95,6 +99,10 @@ func (c *Config) Init() error {
 		return err
 	}
 
+	if err := c.initStorage(); err != nil {
+		return err
+	}
+
 	c.initSettings()
 	c.initHub()
 
@@ -103,6 +111,28 @@ func (c *Config) Init() error {
 	return c.connectDb()
 }
 
+// initStorage initializes storage directories with a random serial.
+func (c *Config) initStorage() error {
+	const serialName = "serial"
+
+	c.serial = rnd.PPID('z')
+
+	storageName := filepath.Join(c.StoragePath(), serialName)
+	backupName := filepath.Join(c.BackupPath(), serialName)
+
+	if data, err := ioutil.ReadFile(storageName); err == nil {
+		c.serial = string(data)
+	} else if data, err := ioutil.ReadFile(backupName); err == nil {
+		c.serial = string(data)
+	} else if err := ioutil.WriteFile(storageName, []byte(c.serial), os.ModePerm); err != nil {
+		return fmt.Errorf("failed creating %s: %s", storageName, err)
+	} else if err := ioutil.WriteFile(backupName, []byte(c.serial), os.ModePerm); err != nil {
+		return fmt.Errorf("failed creating %s: %s", backupName, err)
+	}
+
+	return nil
+}
+
 // Name returns the application name ("PhotoPrism").
 func (c *Config) Name() string {
 	return c.params.Name
@@ -294,7 +324,7 @@ func (c *Config) UpdateHub() {
 
 // initHub initializes PhotoPrism hub config.
 func (c *Config) initHub() {
-	c.hub = hub.NewConfig(c.Version(), c.HubConfigFile())
+	c.hub = hub.NewConfig(c.Version(), c.HubConfigFile(), c.serial)
 
 	if err := c.hub.Load(); err == nil {
 		// Do nothing.
diff --git a/internal/hub/config.go b/internal/hub/config.go
index e5235c705..bc9199f17 100644
--- a/internal/hub/config.go
+++ b/internal/hub/config.go
@@ -30,17 +30,19 @@ type Config struct {
 	Session  string `json:"session" yaml:"session"`
 	Status   string `json:"status" yaml:"status"`
 	Version  string `json:"version" yaml:"version"`
+	Serial   string `json:"serial" yaml:"serial"`
 	FileName string `json:"-" yaml:"-"`
 }
 
 // NewConfig creates a new backend api credentials instance.
-func NewConfig(version string, fileName string) *Config {
+func NewConfig(version, fileName, serial string) *Config {
 	return &Config{
 		Key:      "",
 		Secret:   "",
 		Session:  "",
 		Status:   "",
 		Version:  version,
+		Serial:   serial,
 		FileName: fileName,
 	}
 }
@@ -140,7 +142,7 @@ func (c *Config) Refresh() (err error) {
 		log.Debugf("requesting api key for maps & places from %s", ApiHost())
 	}
 
-	if j, err := json.Marshal(NewRequest(c.Version)); err != nil {
+	if j, err := json.Marshal(NewRequest(c.Version, c.Serial)); err != nil {
 		return err
 	} else if req, err = http.NewRequest(method, url, bytes.NewReader(j)); err != nil {
 		return err
diff --git a/internal/hub/config_test.go b/internal/hub/config_test.go
index 7afb40d9e..4269be6f3 100644
--- a/internal/hub/config_test.go
+++ b/internal/hub/config_test.go
@@ -8,7 +8,7 @@ import (
 
 func TestConfig_MapKey(t *testing.T) {
 	t.Run("success", func(t *testing.T) {
-		c := NewConfig("0.0.0", "testdata/new.yml")
+		c := NewConfig("0.0.0", "testdata/new.yml", "zqkunt22r0bewti9")
 		assert.Equal(t, "", c.MapKey())
 	})
 }
diff --git a/internal/hub/feedback.go b/internal/hub/feedback.go
index 6415f678f..8db0787de 100644
--- a/internal/hub/feedback.go
+++ b/internal/hub/feedback.go
@@ -23,15 +23,17 @@ type Feedback struct {
 	UserAgent     string `json:"UserAgent"`
 	ApiKey        string `json:"ApiKey"`
 	ClientVersion string `json:"ClientVersion"`
+	ClientSerial  string `json:"ClientSerial"`
 	ClientOS      string `json:"ClientOS"`
 	ClientArch    string `json:"ClientArch"`
 	ClientCPU     int    `json:"ClientCPU"`
 }
 
 // NewFeedback creates a new hub feedback instance.
-func NewFeedback(version string) *Feedback {
+func NewFeedback(version, serial string) *Feedback {
 	return &Feedback{
 		ClientVersion: version,
+		ClientSerial:  serial,
 		ClientOS:      runtime.GOOS,
 		ClientArch:    runtime.GOARCH,
 		ClientCPU:     runtime.NumCPU(),
@@ -39,7 +41,7 @@ func NewFeedback(version string) *Feedback {
 }
 
 func (c *Config) SendFeedback(f form.Feedback) (err error) {
-	feedback := NewFeedback(c.Version)
+	feedback := NewFeedback(c.Version, c.Serial)
 	feedback.Category = f.Category
 	feedback.Subject = txt.TrimLen(f.Message, 50)
 	feedback.Message = f.Message
diff --git a/internal/hub/feedback_test.go b/internal/hub/feedback_test.go
index 325c0ba12..6451dd63e 100644
--- a/internal/hub/feedback_test.go
+++ b/internal/hub/feedback_test.go
@@ -9,14 +9,15 @@ import (
 
 func TestNewFeedback(t *testing.T) {
 	t.Run("success", func(t *testing.T) {
-		feedback := NewFeedback("xxx")
+		feedback := NewFeedback("xxx", "zqkunt22r0bewti9")
 		assert.Equal(t, "xxx", feedback.ClientVersion)
+		assert.Equal(t, "zqkunt22r0bewti9", feedback.ClientSerial)
 	})
 }
 
 func TestSendFeedback(t *testing.T) {
 	t.Run("success", func(t *testing.T) {
-		c := NewConfig("0.0.0", "testdata/new.yml")
+		c := NewConfig("0.0.0", "testdata/new.yml", "zqkunt22r0bewti9")
 
 		feedback := Feedback{
 			Category:      "Bug Report",
diff --git a/internal/hub/hub_test.go b/internal/hub/hub_test.go
index c9602eab6..24e9a09f4 100644
--- a/internal/hub/hub_test.go
+++ b/internal/hub/hub_test.go
@@ -49,13 +49,13 @@ func Token(size uint) string {
 }
 
 func TestNewConfig(t *testing.T) {
-	c := NewConfig("0.0.0", "testdata/new.yml")
+	c := NewConfig("0.0.0", "testdata/new.yml", "zqkunt22r0bewti9")
 
 	assert.IsType(t, &Config{}, c)
 }
 
 func TestNewRequest(t *testing.T) {
-	r := NewRequest("0.0.0")
+	r := NewRequest("0.0.0", "zqkunt22r0bewti9")
 
 	assert.IsType(t, &Request{}, r)
 
@@ -72,7 +72,7 @@ func TestConfig_Refresh(t *testing.T) {
 	t.Run("success", func(t *testing.T) {
 		fileName := fmt.Sprintf("testdata/hub.%s.yml", Token(8))
 
-		c := NewConfig("0.0.0", fileName)
+		c := NewConfig("0.0.0", fileName, "zqkunt22r0bewti9")
 
 		if err := c.Refresh(); err != nil {
 			t.Fatal(err)
@@ -122,7 +122,7 @@ func TestConfig_Refresh(t *testing.T) {
 
 func TestConfig_DecodeSession(t *testing.T) {
 	t.Run("hub3.yml", func(t *testing.T) {
-		c := NewConfig("0.0.0", "testdata/hub3.yml")
+		c := NewConfig("0.0.0", "testdata/hub3.yml", "zqkunt22r0bewti9")
 
 		err := c.Load()
 
@@ -138,7 +138,7 @@ func TestConfig_DecodeSession(t *testing.T) {
 
 func TestConfig_Load(t *testing.T) {
 	t.Run("hub1.yml", func(t *testing.T) {
-		c := NewConfig("0.0.0", "testdata/hub1.yml")
+		c := NewConfig("0.0.0", "testdata/hub1.yml", "zqkunt22r0bewti9")
 
 		if err := c.Load(); err != nil {
 			t.Logf(err.Error())
@@ -151,7 +151,7 @@ func TestConfig_Load(t *testing.T) {
 		assert.Equal(t, "0.0.0", c.Version)
 	})
 	t.Run("hub2.yml", func(t *testing.T) {
-		c := NewConfig("0.0.0", "testdata/hub2.yml")
+		c := NewConfig("0.0.0", "testdata/hub2.yml", "zqkunt22r0bewti9")
 
 		if err := c.Load(); err != nil {
 			t.Logf(err.Error())
@@ -164,7 +164,7 @@ func TestConfig_Load(t *testing.T) {
 		assert.Equal(t, "200925-f8e2b580-Darwin-i386-DEBUG", c.Version)
 	})
 	t.Run("not existing filename", func(t *testing.T) {
-		c := NewConfig("0.0.0", "testdata/hub_xxx.yml")
+		c := NewConfig("0.0.0", "testdata/hub_xxx.yml", "zqkunt22r0bewti9")
 
 		if err := c.Load(); err == nil {
 			t.Fatal("file should not exist")
@@ -180,7 +180,7 @@ func TestConfig_Save(t *testing.T) {
 	t.Run("existing filename", func(t *testing.T) {
 		assert.FileExists(t, "testdata/hub1.yml")
 
-		c := NewConfig("0.0.0", "testdata/hub1.yml")
+		c := NewConfig("0.0.0", "testdata/hub1.yml", "zqkunt22r0bewti9")
 
 		if err := c.Load(); err != nil {
 			t.Logf(err.Error())
@@ -219,7 +219,7 @@ func TestConfig_Save(t *testing.T) {
 		assert.Equal(t, "0.0.0", c.Version)
 	})
 	t.Run("not existing filename", func(t *testing.T) {
-		c := NewConfig("0.0.0", "testdata/hub_new.yml")
+		c := NewConfig("0.0.0", "testdata/hub_new.yml", "zqkunt22r0bewti9")
 		c.Key = "F60F5B25D59C397989E3CD374F81CDD7710A4FCA"
 		c.Secret = "foo"
 		c.Session = "bar"
diff --git a/internal/hub/request.go b/internal/hub/request.go
index 046454c0f..b1c690d63 100644
--- a/internal/hub/request.go
+++ b/internal/hub/request.go
@@ -10,15 +10,17 @@ var ServiceURL = "https://hub.photoprism.app/v1/hello"
 // Backend api credentials request incl basic runtime specs.
 type Request struct {
 	ClientVersion string `json:"ClientVersion"`
+	ClientSerial  string `json:"ClientSerial"`
 	ClientOS      string `json:"ClientOS"`
 	ClientArch    string `json:"ClientArch"`
 	ClientCPU     int    `json:"ClientCPU"`
 }
 
 // NewRequest creates a new hub key request instance.
-func NewRequest(version string) *Request {
+func NewRequest(version, serial string) *Request {
 	return &Request{
 		ClientVersion: version,
+		ClientSerial:  serial,
 		ClientOS:      runtime.GOOS,
 		ClientArch:    runtime.GOARCH,
 		ClientCPU:     runtime.NumCPU(),