diff --git a/.mockery.yaml b/.mockery.yaml
index 9adcc90..b5f727d 100644
--- a/.mockery.yaml
+++ b/.mockery.yaml
@@ -2,6 +2,11 @@ with-expecter: True
 dir: mocks/
 outpkg: mocks
 packages:
+  me-fit/service:
+    interfaces:
+      RandomGenerator:
+      Clock:
+      MailService:
   me-fit/db:
     interfaces:
       DbAuth:
diff --git a/db/auth.go b/db/auth.go
index 76c010b..d99a2b0 100644
--- a/db/auth.go
+++ b/db/auth.go
@@ -6,6 +6,7 @@ import (
 
 	"database/sql"
 	"errors"
+	"strings"
 	"time"
 
 	"github.com/google/uuid"
@@ -13,6 +14,7 @@ import (
 
 var (
 	ErrUserNotFound = errors.New("User not found")
+	ErrUserExists   = errors.New("User already exists")
 )
 
 type User struct {
@@ -41,6 +43,10 @@ func NewUser(id uuid.UUID, email string, emailVerified bool, emailVerifiedAt *ti
 
 type DbAuth interface {
 	GetUser(email string) (*User, error)
+	InsertUser(user *User) error
+
+	GetEmailVerificationToken(userId uuid.UUID) (string, error)
+	InsertEmailVerificationToken(userId uuid.UUID, token string) error
 }
 
 type DbAuthSqlite struct {
@@ -77,3 +83,49 @@ func (db DbAuthSqlite) GetUser(email string) (*User, error) {
 
 	return NewUser(userId, email, emailVerified, emailVerifiedAt, isAdmin, password, salt, createdAt), nil
 }
+func (db DbAuthSqlite) InsertUser(user *User) error {
+	_, err := db.db.Exec(`
+		INSERT INTO user (user_uuid, email, email_verified, email_verified_at, is_admin, password, salt, created_at) 
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
+		user.Id, user.Email, user.EmailVerified, user.EmailVerifiedAt, user.IsAdmin, user.Password, user.Salt, user.CreateAt)
+
+	if err != nil {
+		if strings.Contains(err.Error(), "email") {
+			return ErrUserExists
+		}
+
+		utils.LogError("SQL error InsertUser", err)
+		return types.ErrInternal
+	}
+
+	return nil
+}
+
+func (db DbAuthSqlite) GetEmailVerificationToken(userId uuid.UUID) (string, error) {
+	var token string
+
+	err := db.db.QueryRow(`
+		SELECT token 
+		FROM user_token 
+		WHERE user_uuid = ? 
+		AND type = 'email_verify'`, userId).Scan(&token)
+
+	if err != nil && err != sql.ErrNoRows {
+		utils.LogError("Could not get token", err)
+		return "", types.ErrInternal
+	}
+
+	return token, nil
+}
+func (db DbAuthSqlite) InsertEmailVerificationToken(userId uuid.UUID, token string) error {
+	_, err := db.db.Exec(`
+		INSERT INTO user_token (user_uuid, type, token, created_at) 
+		VALUES (?, 'email_verify', ?, datetime())`, userId, token)
+
+	if err != nil {
+		utils.LogError("Could not insert token", err)
+		return types.ErrInternal
+	}
+
+	return nil
+}
diff --git a/db/auth_test.go b/db/auth_test.go
index 48c6168..d47c319 100644
--- a/db/auth_test.go
+++ b/db/auth_test.go
@@ -4,11 +4,11 @@ import (
 	"me-fit/utils"
 
 	"database/sql"
-	"reflect"
 	"testing"
 	"time"
 
 	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
 )
 
 func setupDb(t *testing.T) *sql.DB {
@@ -16,6 +16,9 @@ func setupDb(t *testing.T) *sql.DB {
 	if err != nil {
 		t.Fatalf("Error opening database: %v", err)
 	}
+	t.Cleanup(func() {
+		db.Close()
+	})
 
 	err = utils.RunMigrations(db, "../")
 	if err != nil {
@@ -25,26 +28,41 @@ func setupDb(t *testing.T) *sql.DB {
 	return db
 }
 
-func TestGetUser(t *testing.T) {
+func TestUser(t *testing.T) {
 	t.Parallel()
 
 	t.Run("should return UserNotFound", func(t *testing.T) {
 		t.Parallel()
 		db := setupDb(t)
-		defer db.Close()
 
 		underTest := DbAuthSqlite{db: db}
 
 		_, err := underTest.GetUser("someNonExistentEmail")
-		if err != ErrUserNotFound {
-			t.Errorf("Expected UserNotFound, got %v", err)
-		}
+		assert.Equal(t, ErrUserNotFound, err)
 	})
 
-	t.Run("should find user in database", func(t *testing.T) {
+	t.Run("should insert and get user", func(t *testing.T) {
+		t.Parallel()
+		db := setupDb(t)
+
+		underTest := DbAuthSqlite{db: db}
+
+		verifiedAt := time.Date(2020, 1, 5, 13, 0, 0, 0, time.UTC)
+		createAt := time.Date(2020, 1, 5, 12, 0, 0, 0, time.UTC)
+		expected := NewUser(uuid.New(), "some@email.de", true, &verifiedAt, false, []byte("somePass"), []byte("someSalt"), createAt)
+
+		err := underTest.InsertUser(expected)
+		assert.Nil(t, err)
+
+		actual, err := underTest.GetUser(expected.Email)
+		assert.Nil(t, err)
+
+		assert.Equal(t, expected, actual)
+	})
+
+	t.Run("should throw error if user already exists", func(t *testing.T) {
 		t.Parallel()
 		db := setupDb(t)
-		defer db.Close()
 
 		underTest := DbAuthSqlite{db: db}
 
@@ -52,22 +70,43 @@ func TestGetUser(t *testing.T) {
 		createAt := time.Date(2020, 1, 5, 12, 0, 0, 0, time.UTC)
 		user := NewUser(uuid.New(), "some@email.de", true, &verifiedAt, false, []byte("somePass"), []byte("someSalt"), createAt)
 
-		_, err := db.Exec(`
-			INSERT INTO user (user_uuid, email, email_verified, email_verified_at, is_admin, password, salt, created_at)
-			VALUES (?, ?, ?, ?, ?, ?, ?, ?)
-		`, user.Id, user.Email, user.EmailVerified, user.EmailVerifiedAt, user.IsAdmin, user.Password, user.Salt, user.CreateAt)
-		if err != nil {
-			t.Fatalf("Error inserting user: %v", err)
-		}
+		err := underTest.InsertUser(user)
+		assert.Nil(t, err)
 
-		actual, err := underTest.GetUser(user.Email)
-		if err != nil {
-			t.Fatalf("Error getting user: %v", err)
-		}
-
-		if !reflect.DeepEqual(user, actual) {
-			t.Errorf("Expected %v, got %v", user, actual)
-		}
+		err = underTest.InsertUser(user)
+		assert.Equal(t, ErrUserExists, err)
+	})
+}
+
+func TestEmailVerification(t *testing.T) {
+	t.Parallel()
+
+	t.Run("should return empty string if no token is safed", func(t *testing.T) {
+		t.Parallel()
+		db := setupDb(t)
+
+		underTest := DbAuthSqlite{db: db}
+
+		token, err := underTest.GetEmailVerificationToken(uuid.New())
+
+		assert.Nil(t, err)
+		assert.Equal(t, "", token)
+	})
+	t.Run("should insert and return token", func(t *testing.T) {
+		t.Parallel()
+		db := setupDb(t)
+
+		underTest := DbAuthSqlite{db: db}
+
+		userId := uuid.New()
+		expectedToken := "someToken"
+
+		err := underTest.InsertEmailVerificationToken(userId, expectedToken)
+		assert.Nil(t, err)
+
+		actualToken, err := underTest.GetEmailVerificationToken(userId)
+		assert.Nil(t, err)
+
+		assert.Equal(t, expectedToken, actualToken)
 	})
-
 }
diff --git a/handler/auth.go b/handler/auth.go
index 9267fee..ea155fb 100644
--- a/handler/auth.go
+++ b/handler/auth.go
@@ -8,6 +8,7 @@ import (
 	"me-fit/utils"
 
 	"database/sql"
+	"errors"
 	"net/http"
 	"time"
 )
@@ -33,13 +34,13 @@ func NewHandlerAuth(db *sql.DB, service service.ServiceAuth, serverSettings *typ
 func (handler HandlerAuthImpl) handle(router *http.ServeMux) {
 	// Don't use auth middleware for these routes, as it makes redirecting very difficult, if the mail is not yet verified
 	router.Handle("/auth/signin", handler.handleSignInPage())
-	router.Handle("/auth/signup", service.HandleSignUpPage(handler.db, handler.serverSettings))
+	router.Handle("/auth/signup", handler.handleSignUpPage())
 	router.Handle("/auth/verify", service.HandleSignUpVerifyPage(handler.db, handler.serverSettings)) // Hint for the user to verify their email
 	router.Handle("/auth/delete-account", service.HandleDeleteAccountPage(handler.db, handler.serverSettings))
 	router.Handle("/auth/verify-email", service.HandleSignUpVerifyResponsePage(handler.db)) // The link contained in the email
 	router.Handle("/auth/change-password", service.HandleChangePasswordPage(handler.db, handler.serverSettings))
 	router.Handle("/auth/reset-password", service.HandleResetPasswordPage(handler.db, handler.serverSettings))
-	router.Handle("/api/auth/signup", service.HandleSignUpComp(handler.db, handler.serverSettings))
+	router.Handle("/api/auth/signup", handler.handleSignUp())
 	router.Handle("/api/auth/signin", handler.handleSignIn())
 	router.Handle("/api/auth/signout", service.HandleSignOutComp(handler.db))
 	router.Handle("/api/auth/delete-account", service.HandleDeleteAccountComp(handler.db, handler.serverSettings))
@@ -74,7 +75,6 @@ func (handler HandlerAuthImpl) handleSignInPage() http.HandlerFunc {
 		}
 	}
 }
-
 func (handler HandlerAuthImpl) handleSignIn() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		user, err := utils.WaitMinimumTime(securityWaitDuration, func() (*service.User, error) {
@@ -112,3 +112,54 @@ func (handler HandlerAuthImpl) handleSignIn() http.HandlerFunc {
 		}
 	}
 }
+
+func (handler HandlerAuthImpl) handleSignUpPage() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		user := utils.GetUserFromSession(handler.db, r)
+
+		if user == nil {
+			userComp := service.UserInfoComp(nil)
+			signUpComp := auth.SignInOrUpComp(false)
+			err := template.Layout(signUpComp, userComp, handler.serverSettings.Environment).Render(r.Context(), w)
+
+			if err != nil {
+				utils.LogError("Failed to render sign up page", err)
+				http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+			}
+
+		} else if !user.EmailVerified {
+			utils.DoRedirect(w, r, "/auth/verify")
+		} else {
+			utils.DoRedirect(w, r, "/")
+		}
+	}
+}
+func (handler HandlerAuthImpl) handleSignUp() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var email = r.FormValue("email")
+		var password = r.FormValue("password")
+
+		_, err := utils.WaitMinimumTime(securityWaitDuration, func() (interface{}, error) {
+			user, err := handler.service.SignUp(email, password)
+			if err != nil {
+				return nil, err
+			}
+
+			go handler.service.SendVerificationMail(user.Id, user.Email)
+			return nil, nil
+		})
+
+		if err != nil {
+			if errors.Is(err, types.ErrInternal) {
+				utils.TriggerToast(w, r, "error", "An error occurred")
+				return
+			} else if errors.Is(err, service.ErrInvalidEmail) {
+				utils.TriggerToast(w, r, "error", "The email provided is invalid")
+				return
+			}
+			// If the "service.ErrAccountExists", then just continue
+		}
+
+		utils.TriggerToast(w, r, "success", "A link to activate your account has been emailed to the address provided.")
+	}
+}
diff --git a/handler/default.go b/handler/default.go
index be45239..ea0cf5a 100644
--- a/handler/default.go
+++ b/handler/default.go
@@ -15,7 +15,12 @@ func GetHandler(d *sql.DB, serverSettings *types.ServerSettings) http.Handler {
 
 	router.HandleFunc("/", service.HandleIndexAnd404(d, serverSettings))
 
-	handlerAuth := NewHandlerAuth(d, service.NewServiceAuthImpl(db.NewDbAuthSqlite(d)), serverSettings)
+	randomGenerator := service.NewRandomGeneratorImpl()
+	clock := service.NewClockImpl()
+	dbAuth := db.NewDbAuthSqlite(d)
+	mailService := service.NewMailServiceImpl(serverSettings)
+	serviceAuth := service.NewServiceAuthImpl(dbAuth, randomGenerator, clock, mailService, serverSettings)
+	handlerAuth := NewHandlerAuth(d, serviceAuth, serverSettings)
 
 	// Serve static files (CSS, JS and images)
 	router.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("./static/"))))
diff --git a/service/auth.go b/service/auth.go
index c9a8cd8..c1f3663 100644
--- a/service/auth.go
+++ b/service/auth.go
@@ -2,7 +2,6 @@ package service
 
 import (
 	"context"
-	"crypto/rand"
 	"crypto/subtle"
 	"database/sql"
 	"errors"
@@ -25,8 +24,10 @@ import (
 )
 
 var (
-	ErrInvaidCredentials  = errors.New("Invalid email or password")
-	ErrPasswordComplexity = errors.New("Password needs to be 8 characters long, contain at least one number, one special, one uppercase and one lowercase character")
+	ErrInvaidCredentials = errors.New("Invalid email or password")
+	ErrInvalidPassword   = errors.New("Password needs to be 8 characters long, contain at least one number, one special, one uppercase and one lowercase character")
+	ErrInvalidEmail      = errors.New("Invalid email")
+	ErrAccountExists     = errors.New("Account already exists")
 )
 
 type User struct {
@@ -45,20 +46,29 @@ func NewUser(user *db.User) *User {
 
 type ServiceAuth interface {
 	SignIn(email string, password string) (*User, error)
+	SignUp(email string, password string) (*User, error)
+	SendVerificationMail(userId uuid.UUID, email string)
 }
 
 type ServiceAuthImpl struct {
-	dbAuth db.DbAuth
+	dbAuth          db.DbAuth
+	randomGenerator RandomGenerator
+	clock           Clock
+	mailService     MailService
+	serverSettings  *types.ServerSettings
 }
 
-func NewServiceAuthImpl(dbAuth db.DbAuth) *ServiceAuthImpl {
+func NewServiceAuthImpl(dbAuth db.DbAuth, randomGenerator RandomGenerator, clock Clock, mailService MailService, serverSettings *types.ServerSettings) *ServiceAuthImpl {
 	return &ServiceAuthImpl{
-		dbAuth: dbAuth,
+		dbAuth:          dbAuth,
+		randomGenerator: randomGenerator,
+		clock:           clock,
+		mailService:     mailService,
+		serverSettings:  serverSettings,
 	}
 }
 
 func (service ServiceAuthImpl) SignIn(email string, password string) (*User, error) {
-
 	user, err := service.dbAuth.GetUser(email)
 	if err != nil {
 		if errors.Is(err, db.ErrUserNotFound) {
@@ -77,30 +87,74 @@ func (service ServiceAuthImpl) SignIn(email string, password string) (*User, err
 	return NewUser(user), nil
 }
 
-// TODO
+func (service ServiceAuthImpl) SignUp(email string, password string) (*User, error) {
+	_, err := mail.ParseAddress(email)
+	if err != nil {
+		return nil, ErrInvalidEmail
+	}
 
-func HandleSignUpPage(db *sql.DB, serverSettings *types.ServerSettings) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		user := utils.GetUserFromSession(db, r)
+	if !isPasswordValid(password) {
+		return nil, ErrInvalidPassword
+	}
 
-		if user == nil {
-			userComp := UserInfoComp(nil)
-			signUpComp := auth.SignInOrUpComp(false)
-			err := template.Layout(signUpComp, userComp, serverSettings.Environment).Render(r.Context(), w)
+	userId, err := service.randomGenerator.UUID()
+	if err != nil {
+		return nil, types.ErrInternal
+	}
 
-			if err != nil {
-				utils.LogError("Failed to render sign up page", err)
-				http.Error(w, "Internal Server Error", http.StatusInternalServerError)
-			}
+	salt, err := service.randomGenerator.Bytes(16)
+	if err != nil {
+		return nil, types.ErrInternal
+	}
 
-		} else if !user.EmailVerified {
-			utils.DoRedirect(w, r, "/auth/verify")
+	hash := GetHashPassword(password, salt)
+
+	dbUser := db.NewUser(userId, email, false, nil, false, hash, salt, service.clock.Now())
+
+	err = service.dbAuth.InsertUser(dbUser)
+	if err != nil {
+		if err == db.ErrUserExists {
+			return nil, ErrAccountExists
 		} else {
-			utils.DoRedirect(w, r, "/")
+			return nil, types.ErrInternal
 		}
 	}
+
+	return NewUser(dbUser), nil
 }
 
+func (service ServiceAuthImpl) SendVerificationMail(userId uuid.UUID, email string) {
+	var token string
+
+	token, err := service.dbAuth.GetEmailVerificationToken(userId)
+	if err != nil {
+		return
+	}
+
+	if token == "" {
+		token, err := service.randomGenerator.String(32)
+		if err != nil {
+			return
+		}
+
+		err = service.dbAuth.InsertEmailVerificationToken(userId, token)
+		if err != nil {
+			return
+		}
+	}
+
+	var w strings.Builder
+	err = tempMail.Register(service.serverSettings.BaseUrl, token).Render(context.Background(), &w)
+	if err != nil {
+		utils.LogError("Could not render welcome email", err)
+		return
+	}
+
+	service.mailService.SendMail(email, "Welcome to ME-FIT", w.String())
+}
+
+// TODO
+
 func HandleSignUpVerifyPage(db *sql.DB, serverSettings *types.ServerSettings) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		user := utils.GetUserFromSession(db, r)
@@ -227,69 +281,6 @@ func UserInfoComp(user *types.User) templ.Component {
 	}
 }
 
-func HandleSignUpComp(db *sql.DB, serverSettings *types.ServerSettings) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		var email = r.FormValue("email")
-		var password = r.FormValue("password")
-
-		_, err := mail.ParseAddress(email)
-		if err != nil {
-			http.Error(w, "Invalid email", http.StatusBadRequest)
-			return
-		}
-
-		err = checkPassword(password)
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusBadRequest)
-			return
-		}
-
-		userId, err := uuid.NewRandom()
-		if err != nil {
-			utils.LogError("Could not generate UUID", err)
-			auth.Error("Internal Server Error").Render(r.Context(), w)
-			return
-		}
-
-		salt := make([]byte, 16)
-		_, err = rand.Read(salt)
-		if err != nil {
-			utils.LogError("Could not generate salt", err)
-			auth.Error("Internal Server Error").Render(r.Context(), w)
-			return
-		}
-
-		hash := GetHashPassword(password, salt)
-
-		_, err = db.Exec("INSERT INTO user (user_uuid, email, email_verified, is_admin, password, salt, created_at) VALUES (?, ?, FALSE, FALSE, ?, ?, datetime())", userId, email, hash, salt)
-		if err != nil {
-			// This does leak information about the email being in use, though not specifically stated
-			// It needs to be refacoteres to "If the email is not already in use, an email has been send to your address", or something
-			// The happy path, currently a redirect, needs to send the same message!
-			// Then it is also important to have the same compute time in both paths
-			// Otherwise an attacker could guess emails when comparing the response time
-			if strings.Contains(err.Error(), "email") {
-				auth.Error("Bad Request").Render(r.Context(), w)
-				return
-			}
-
-			utils.LogError("Could not insert user", err)
-			auth.Error("Internal Server Error").Render(r.Context(), w)
-			return
-		}
-
-		err = TryCreateSessionAndSetCookie(r, w, db, userId)
-		if err != nil {
-			return
-		}
-
-		// Send verification email as a goroutine
-		go sendVerificationEmail(db, userId.String(), email, serverSettings)
-
-		utils.DoRedirect(w, r, "/auth/verify")
-	}
-}
-
 func HandleSignOutComp(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		user := utils.GetUserFromSession(db, r)
@@ -320,7 +311,7 @@ func HandleSignOutComp(db *sql.DB) http.HandlerFunc {
 }
 
 func HandleDeleteAccountComp(db *sql.DB, serverSettings *types.ServerSettings) http.HandlerFunc {
-	mailService := NewMailService(serverSettings)
+	mailService := NewMailServiceImpl(serverSettings)
 	return func(w http.ResponseWriter, r *http.Request) {
 		user := utils.GetUserFromSession(db, r)
 		if user == nil {
@@ -394,7 +385,8 @@ func HandleVerifyResendComp(db *sql.DB, serverSettings *types.ServerSettings) ht
 			return
 		}
 
-		go sendVerificationEmail(db, user.Id.String(), user.Email, serverSettings)
+		// TODO
+		// go sendVerificationEmail(db, user.Id.String(), user.Email, serverSettings)
 
 		w.Write([]byte("<p class=\"mt-8\">Verification email sent</p>"))
 	}
@@ -412,9 +404,8 @@ func HandleChangePasswordComp(db *sql.DB) http.HandlerFunc {
 		currPass := r.FormValue("current-password")
 		newPass := r.FormValue("new-password")
 
-		err := checkPassword(newPass)
-		if err != nil {
-			utils.TriggerToast(w, r, "error", err.Error())
+		if !isPasswordValid(newPass) {
+			utils.TriggerToast(w, r, "error", ErrInvalidPassword.Error())
 			return
 		}
 
@@ -428,7 +419,7 @@ func HandleChangePasswordComp(db *sql.DB) http.HandlerFunc {
 			salt       []byte
 		)
 
-		err = db.QueryRow("SELECT password, salt FROM user WHERE user_uuid = ?", user.Id).Scan(&storedHash, &salt)
+		err := db.QueryRow("SELECT password, salt FROM user WHERE user_uuid = ?", user.Id).Scan(&storedHash, &salt)
 		if err != nil {
 			utils.LogError("Could not get password", err)
 			utils.TriggerToast(w, r, "error", "Internal Server Error")
@@ -472,9 +463,8 @@ func HandleActualResetPasswordComp(db *sql.DB) http.HandlerFunc {
 
 		newPass := r.FormValue("new-password")
 
-		err = checkPassword(newPass)
-		if err != nil {
-			utils.TriggerToast(w, r, "error", err.Error())
+		if !isPasswordValid(newPass) {
+			utils.TriggerToast(w, r, "error", ErrInvalidPassword.Error())
 			return
 		}
 
@@ -516,8 +506,9 @@ func HandleActualResetPasswordComp(db *sql.DB) http.HandlerFunc {
 		utils.TriggerToast(w, r, "success", "Password changed")
 	}
 }
+
 func HandleResetPasswordComp(db *sql.DB, serverSettings *types.ServerSettings) http.HandlerFunc {
-	mailService := NewMailService(serverSettings)
+	mailService := NewMailServiceImpl(serverSettings)
 	return func(w http.ResponseWriter, r *http.Request) {
 
 		email := r.FormValue("email")
@@ -526,9 +517,8 @@ func HandleResetPasswordComp(db *sql.DB, serverSettings *types.ServerSettings) h
 			return
 		}
 
-		token, err := utils.RandomToken()
+		token, err := NewRandomGeneratorImpl().String(32)
 		if err != nil {
-			utils.LogError("Could not generate token", err)
 			return
 		}
 
@@ -566,43 +556,9 @@ func HandleResetPasswordComp(db *sql.DB, serverSettings *types.ServerSettings) h
 	}
 }
 
-func sendVerificationEmail(db *sql.DB, userId string, email string, serverSettings *types.ServerSettings) {
-
-	var token string
-	err := db.QueryRow("SELECT token FROM user_token WHERE user_uuid = ? AND type = 'email_verify'", userId).Scan(&token)
-	if err != nil && err != sql.ErrNoRows {
-		utils.LogError("Could not get token", err)
-		return
-	}
-
-	if token == "" {
-		token, err := utils.RandomToken()
-		if err != nil {
-			utils.LogError("Could not generate token", err)
-			return
-		}
-
-		_, err = db.Exec("INSERT INTO user_token (user_uuid, type, token, created_at) VALUES (?, 'email_verify', ?, datetime())", userId, token)
-		if err != nil {
-			utils.LogError("Could not insert token", err)
-			return
-		}
-	}
-
-	var w strings.Builder
-	err = tempMail.Register(serverSettings.BaseUrl, token).Render(context.Background(), &w)
-	if err != nil {
-		utils.LogError("Could not render welcome email", err)
-		return
-	}
-	mailService := NewMailService(serverSettings)
-	mailService.SendMail(email, "Welcome to ME-FIT", w.String())
-}
-
 func TryCreateSessionAndSetCookie(r *http.Request, w http.ResponseWriter, db *sql.DB, user_uuid uuid.UUID) error {
-	sessionId, err := utils.RandomToken()
+	sessionId, err := NewRandomGeneratorImpl().String(32)
 	if err != nil {
-		utils.LogError("Could not generate session ID", err)
 		return types.ErrInternal
 	}
 
@@ -637,15 +593,15 @@ func GetHashPassword(password string, salt []byte) []byte {
 	return argon2.IDKey([]byte(password), salt, 1, 64*1024, 1, 16)
 }
 
-func checkPassword(password string) error {
+func isPasswordValid(password string) bool {
 
 	if len(password) < 8 ||
 		!strings.ContainsAny(password, "0123456789") ||
 		!strings.ContainsAny(password, "ABCDEFGHIJKLMNOPQRSTUVWXYZ") ||
 		!strings.ContainsAny(password, "abcdefghijklmnopqrstuvwxyz") ||
 		!strings.ContainsAny(password, "!@#$%^&*()_+-=[]{}\\|;:'\",.<>/?") {
-		return ErrPasswordComplexity
+		return false
 	} else {
-		return nil
+		return true
 	}
 }
diff --git a/service/auth_test.go b/service/auth_test.go
index 0e12e14..aeede82 100644
--- a/service/auth_test.go
+++ b/service/auth_test.go
@@ -2,23 +2,26 @@ package service
 
 import (
 	"me-fit/db"
-	m "me-fit/mocks"
+	"me-fit/mocks"
 	"me-fit/types"
+	"strings"
 
 	"errors"
 	"testing"
 	"time"
 
 	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
 )
 
 func TestSignIn(t *testing.T) {
+
 	t.Parallel()
 	t.Run("should return user if password is correct", func(t *testing.T) {
 		t.Parallel()
 		salt := []byte("salt")
 		verifiedAt := time.Date(2020, 1, 2, 0, 0, 0, 0, time.UTC)
-
 		user := db.NewUser(
 			uuid.New(),
 			"test@test.de",
@@ -30,30 +33,31 @@ func TestSignIn(t *testing.T) {
 			time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC),
 		)
 
-		mockDbAuth := m.NewMockDbAuth(t)
+		mockDbAuth := mocks.NewMockDbAuth(t)
 		mockDbAuth.EXPECT().GetUser("test@test.de").Return(user, nil)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
 
-		underTest := NewServiceAuthImpl(mockDbAuth)
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
 
 		actualUser, err := underTest.SignIn(user.Email, "password")
-		if err != nil {
-			t.Errorf("Expected nil, got %v", err)
-		}
+		assert.Nil(t, err)
 
 		expectedUser := User{
 			Id:            user.Id,
 			Email:         user.Email,
 			EmailVerified: user.EmailVerified,
 		}
-		if *actualUser != expectedUser {
-			t.Errorf("Expected %v, got %v", expectedUser, actualUser)
-		}
+
+		assert.Equal(t, expectedUser, *actualUser)
 	})
 
 	t.Run("should return ErrInvalidCretentials if password is not correct", func(t *testing.T) {
 		t.Parallel()
 		salt := []byte("salt")
 		verifiedAt := time.Date(2020, 1, 2, 0, 0, 0, 0, time.UTC)
+
 		user := db.NewUser(
 			uuid.New(),
 			"test@test.de",
@@ -65,38 +69,178 @@ func TestSignIn(t *testing.T) {
 			time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC),
 		)
 
-		mockDbAuth := m.NewMockDbAuth(t)
+		mockDbAuth := mocks.NewMockDbAuth(t)
 		mockDbAuth.EXPECT().GetUser(user.Email).Return(user, nil)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
 
-		underTest := NewServiceAuthImpl(mockDbAuth)
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
 
 		_, err := underTest.SignIn("test@test.de", "wrong password")
-		if err != ErrInvaidCredentials {
-			t.Errorf("Expected %v, got %v", ErrInvaidCredentials, err)
-		}
+
+		assert.Equal(t, ErrInvaidCredentials, err)
 	})
 	t.Run("should return ErrInvalidCretentials if user has not been found", func(t *testing.T) {
 		t.Parallel()
-		mockDbAuth := m.NewMockDbAuth(t)
-		mockDbAuth.EXPECT().GetUser("test").Return(nil, db.ErrUserNotFound)
 
-		underTest := NewServiceAuthImpl(mockDbAuth)
+		mockDbAuth := mocks.NewMockDbAuth(t)
+		mockDbAuth.EXPECT().GetUser("test").Return(nil, db.ErrUserNotFound)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
+
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
 
 		_, err := underTest.SignIn("test", "test")
-		if err != ErrInvaidCredentials {
-			t.Errorf("Expected %v, got %v", ErrInvaidCredentials, err)
-		}
+		assert.Equal(t, ErrInvaidCredentials, err)
 	})
 	t.Run("should forward ErrInternal on any other error", func(t *testing.T) {
 		t.Parallel()
-		mockDbAuth := m.NewMockDbAuth(t)
-		mockDbAuth.EXPECT().GetUser("test").Return(nil, errors.New("Some error"))
 
-		underTest := NewServiceAuthImpl(mockDbAuth)
+		mockDbAuth := mocks.NewMockDbAuth(t)
+		mockDbAuth.EXPECT().GetUser("test").Return(nil, errors.New("Some undefined error"))
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
+
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
 
 		_, err := underTest.SignIn("test", "test")
-		if err != types.ErrInternal {
-			t.Errorf("Expected %v, got %v", types.ErrInternal, err)
-		}
+
+		assert.Equal(t, types.ErrInternal, err)
+	})
+}
+
+func TestSignUp(t *testing.T) {
+	t.Parallel()
+	t.Run("should check for correct email address", func(t *testing.T) {
+		t.Parallel()
+
+		mockDbAuth := mocks.NewMockDbAuth(t)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
+
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
+
+		_, err := underTest.SignUp("invalid email address", "SomeStrongPassword123!")
+
+		assert.Equal(t, ErrInvalidEmail, err)
+	})
+	t.Run("should check for password complexity", func(t *testing.T) {
+		t.Parallel()
+
+		mockDbAuth := mocks.NewMockDbAuth(t)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
+
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
+
+		weakPasswords := []string{
+			"123!ab", // too short
+			"no_upper_case_123",
+			"NO_LOWER_CASE_123",
+			"noSpecialChar123",
+		}
+
+		for _, password := range weakPasswords {
+			_, err := underTest.SignUp("some@valid.email", password)
+			assert.Equal(t, ErrInvalidPassword, err)
+		}
+	})
+	t.Run("should signup correctly", func(t *testing.T) {
+		t.Parallel()
+
+		mockDbAuth := mocks.NewMockDbAuth(t)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
+
+		expected := User{
+			Id:            uuid.New(),
+			Email:         "some@valid.email",
+			EmailVerified: false,
+		}
+
+		random := NewRandomGeneratorImpl()
+		salt, err := random.Bytes(16)
+		assert.Nil(t, err)
+		password := "SomeStrongPassword123!"
+
+		mockRandom.EXPECT().UUID().Return(expected.Id, nil)
+		mockRandom.EXPECT().Bytes(16).Return(salt, nil)
+
+		createTime := time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)
+
+		mockClock.EXPECT().Now().Return(createTime)
+
+		mockDbAuth.EXPECT().InsertUser(db.NewUser(expected.Id, expected.Email, false, nil, false, GetHashPassword(password, salt), salt, createTime)).Return(nil)
+
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
+
+		actual, err := underTest.SignUp(expected.Email, password)
+
+		assert.Nil(t, err)
+
+		assert.Equal(t, expected, *actual)
+	})
+	t.Run("should return ErrAccountExists", func(t *testing.T) {
+		t.Parallel()
+
+		mockDbAuth := mocks.NewMockDbAuth(t)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
+
+		user := User{
+			Id:    uuid.New(),
+			Email: "some@valid.email",
+		}
+
+		random := NewRandomGeneratorImpl()
+		salt, err := random.Bytes(16)
+		assert.Nil(t, err)
+		password := "SomeStrongPassword123!"
+
+		mockRandom.EXPECT().UUID().Return(user.Id, nil)
+		mockRandom.EXPECT().Bytes(16).Return(salt, nil)
+
+		createTime := time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)
+
+		mockClock.EXPECT().Now().Return(createTime)
+
+		mockDbAuth.EXPECT().InsertUser(db.NewUser(user.Id, user.Email, false, nil, false, GetHashPassword(password, salt), salt, createTime)).Return(db.ErrUserExists)
+
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
+
+		_, err = underTest.SignUp(user.Email, password)
+		assert.Equal(t, ErrAccountExists, err)
+	})
+}
+
+func TestSendVerificationMail(t *testing.T) {
+
+	t.Parallel()
+	t.Run("should use stored token and send mail", func(t *testing.T) {
+		t.Parallel()
+
+		token := "someRandomTokenToUse"
+		email := "some@email.de"
+		userId := uuid.New()
+
+		mockDbAuth := mocks.NewMockDbAuth(t)
+		mockRandom := mocks.NewMockRandomGenerator(t)
+		mockClock := mocks.NewMockClock(t)
+		mockMail := mocks.NewMockMailService(t)
+
+		mockDbAuth.EXPECT().GetEmailVerificationToken(userId).Return(token, nil)
+
+		mockMail.EXPECT().SendMail(email, "Welcome to ME-FIT", mock.MatchedBy(func(message string) bool { return strings.Contains(message, token) })).Return(nil)
+
+		underTest := NewServiceAuthImpl(mockDbAuth, mockRandom, mockClock, mockMail, &types.ServerSettings{})
+
+		underTest.SendVerificationMail(userId, email)
 	})
 }
diff --git a/service/clock.go b/service/clock.go
new file mode 100644
index 0000000..cf7cae9
--- /dev/null
+++ b/service/clock.go
@@ -0,0 +1,17 @@
+package service
+
+import "time"
+
+type Clock interface {
+	Now() time.Time
+}
+
+type ClockImpl struct{}
+
+func NewClockImpl() Clock {
+	return &ClockImpl{}
+}
+
+func (c *ClockImpl) Now() time.Time {
+	return time.Now()
+}
diff --git a/service/mail.go b/service/mail.go
index f60d0b4..0505edb 100644
--- a/service/mail.go
+++ b/service/mail.go
@@ -6,15 +6,19 @@ import (
 	"net/smtp"
 )
 
-type MailService struct {
+type MailService interface {
+	SendMail(to string, subject string, message string) error
+}
+
+type MailServiceImpl struct {
 	serverSettings *types.ServerSettings
 }
 
-func NewMailService(serverSettings *types.ServerSettings) MailService {
-	return MailService{serverSettings: serverSettings}
+func NewMailServiceImpl(serverSettings *types.ServerSettings) MailServiceImpl {
+	return MailServiceImpl{serverSettings: serverSettings}
 }
 
-func (m MailService) SendMail(to string, subject string, message string) error {
+func (m MailServiceImpl) SendMail(to string, subject string, message string) error {
 	if m.serverSettings.Smtp == nil {
 		return nil
 	}
diff --git a/service/random_generator.go b/service/random_generator.go
new file mode 100644
index 0000000..4e4e4c5
--- /dev/null
+++ b/service/random_generator.go
@@ -0,0 +1,48 @@
+package service
+
+import (
+	"me-fit/types"
+
+	"crypto/rand"
+	"encoding/base64"
+	"log/slog"
+
+	"github.com/google/uuid"
+)
+
+type RandomGenerator interface {
+	Bytes(size int) ([]byte, error)
+	String(size int) (string, error)
+	UUID() (uuid.UUID, error)
+}
+
+type RandomGeneratorImpl struct {
+}
+
+func NewRandomGeneratorImpl() *RandomGeneratorImpl {
+	return &RandomGeneratorImpl{}
+}
+
+func (r *RandomGeneratorImpl) Bytes(size int) ([]byte, error) {
+	b := make([]byte, 32)
+	_, err := rand.Read(b)
+	if err != nil {
+		slog.Error("Error generating random bytes: " + err.Error())
+		return []byte{}, types.ErrInternal
+	}
+
+	return b, nil
+}
+
+func (r *RandomGeneratorImpl) String(size int) (string, error) {
+	bytes, err := r.Bytes(size)
+	if err != nil {
+		return "", types.ErrInternal
+	}
+
+	return base64.StdEncoding.EncodeToString(bytes), nil
+}
+
+func (r *RandomGeneratorImpl) UUID() (uuid.UUID, error) {
+	return uuid.NewRandom()
+}
diff --git a/utils/ctypto.go b/utils/ctypto.go
deleted file mode 100644
index 4f3cffe..0000000
--- a/utils/ctypto.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package utils
-
-import (
-	"crypto/rand"
-	"encoding/base64"
-)
-
-func RandomToken() (string, error) {
-	b := make([]byte, 32)
-	_, err := rand.Read(b)
-	if err != nil {
-		return "", err
-	}
-
-	return base64.StdEncoding.EncodeToString(b), nil
-}