diff --git a/README.md b/README.md
index 414146a..e873a73 100644
--- a/README.md
+++ b/README.md
@@ -1,14 +1,11 @@
-# Auth microservice
+# Pye Auth
 
 **Mission**: Science compels us to create a microservice!
 
-This is the repository for my **JWT auth microservice assignment**
+This is the repository for my **JWT authentication microservice**
 with(out) blazingly fast cloud-native web3 memory-safe blockchain reactive AI
 (insert a dozen more buzzwords of your choosing) technologies.
 
-This should be done by **October 17th 2024**. Or, at the very least,
-in a state that proves I am competent Go developer.
-
 ## Usage
 
 ```
@@ -33,6 +30,7 @@ Use "pye [command] --help" for more information about a command.
 
 ## Technologies used
 
-* **Storage** - [SQLite](https://github.com/mattn/go-sqlite3) and a PEM file
+* **Storage** - [SQLite](https://github.com/mattn/go-sqlite3) and a
+[PEM](https://en.wikipedia.org/wiki/Privacy-Enhanced_Mail) file
 * **HTTP routing** - [Chi](https://go-chi.io), just for logging...
 * **CLI management** - [Cobra](https://cobra.dev/)
\ No newline at end of file
diff --git a/cmd/find_user.go b/internal/app/find.go
similarity index 85%
rename from cmd/find_user.go
rename to internal/app/find.go
index c852ea0..df7fc61 100644
--- a/cmd/find_user.go
+++ b/internal/app/find.go
@@ -1,9 +1,10 @@
-package cmd
+package app
 
 import (
 	"fmt"
 
-	"git.a71.su/Andrew71/pye/storage"
+	"git.a71.su/Andrew71/pye/internal/models/user"
+	"git.a71.su/Andrew71/pye/internal/storage"
 	"github.com/spf13/cobra"
 )
 
@@ -20,7 +21,7 @@ var findUserCmd = &cobra.Command{
 }
 
 func findUser(cmd *cobra.Command, args []string) {
-	var user storage.User
+	var user user.User
 	var ok bool
 	if args[0] == "email" {
 		user, ok = storage.Data.ByEmail(args[1])
diff --git a/cmd/root.go b/internal/app/root.go
similarity index 73%
rename from cmd/root.go
rename to internal/app/root.go
index c8f97ff..cc5961c 100644
--- a/cmd/root.go
+++ b/internal/app/root.go
@@ -1,21 +1,21 @@
-package cmd
+package app
 
 import (
 	"fmt"
 	"os"
 
-	"git.a71.su/Andrew71/pye/auth"
-	"git.a71.su/Andrew71/pye/config"
-	"git.a71.su/Andrew71/pye/logging"
-	"git.a71.su/Andrew71/pye/storage"
-	"git.a71.su/Andrew71/pye/storage/sqlite"
+	"git.a71.su/Andrew71/pye/internal/auth"
+	"git.a71.su/Andrew71/pye/internal/config"
+	"git.a71.su/Andrew71/pye/internal/logging"
+	"git.a71.su/Andrew71/pye/internal/storage"
+	"git.a71.su/Andrew71/pye/internal/storage/sqlite"
 	"github.com/spf13/cobra"
 )
 
 var rootCmd = &cobra.Command{
 	Use:   "pye",
 	Short: "Pye is a simple JWT system",
-	Long:  `A bare-bones authentication system built by Andrew71 as an assignment`,
+	Long:  `A bare-bones authentication system with RS256`,
 }
 
 var (
diff --git a/cmd/serve.go b/internal/app/serve.go
similarity index 90%
rename from cmd/serve.go
rename to internal/app/serve.go
index 7eb409b..07f198b 100644
--- a/cmd/serve.go
+++ b/internal/app/serve.go
@@ -1,12 +1,12 @@
-package cmd
+package app
 
 import (
 	"log/slog"
 	"net/http"
 	"strconv"
 
-	"git.a71.su/Andrew71/pye/auth"
-	"git.a71.su/Andrew71/pye/config"
+	"git.a71.su/Andrew71/pye/internal/auth"
+	"git.a71.su/Andrew71/pye/internal/config"
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
 	"github.com/spf13/cobra"
diff --git a/cmd/verify.go b/internal/app/verify.go
similarity index 95%
rename from cmd/verify.go
rename to internal/app/verify.go
index 8492897..081c288 100644
--- a/cmd/verify.go
+++ b/internal/app/verify.go
@@ -1,11 +1,11 @@
-package cmd
+package app
 
 import (
 	"fmt"
 	"log/slog"
 	"os"
 
-	"git.a71.su/Andrew71/pye/auth"
+	"git.a71.su/Andrew71/pye/internal/auth"
 	"github.com/golang-jwt/jwt/v5"
 	"github.com/spf13/cobra"
 )
diff --git a/auth/auth.go b/internal/auth/auth.go
similarity index 85%
rename from auth/auth.go
rename to internal/auth/auth.go
index f38c586..657b169 100644
--- a/auth/auth.go
+++ b/internal/auth/auth.go
@@ -1,12 +1,13 @@
 package auth
 
 import (
+	"errors"
 	"log/slog"
 	"net/http"
 	"net/mail"
 	"strings"
 
-	"git.a71.su/Andrew71/pye/storage"
+	"git.a71.su/Andrew71/pye/internal/storage"
 )
 
 func validEmail(email string) bool {
@@ -25,7 +26,7 @@ func Register(w http.ResponseWriter, r *http.Request) {
 	if ok {
 		email = strings.TrimSpace(email)
 		password = strings.TrimSpace(password)
-		if !(validEmail(email) && validPass(password) && !storage.Data.Taken(email)) {
+		if !(validEmail(email) && validPass(password)) {
 			slog.Debug("outcome",
 				"valid_email", validEmail(email),
 				"valid_pass", validPass(password),
@@ -35,12 +36,15 @@ func Register(w http.ResponseWriter, r *http.Request) {
 		}
 		err := storage.Data.Add(email, password)
 		if err != nil {
-			slog.Error("error adding a new user", "error", err)
-			http.Error(w, "error adding a new user", http.StatusInternalServerError)
+			if errors.Is(err, storage.ErrExist) {
+				http.Error(w, "invalid auth credentials", http.StatusBadRequest)
+			} else {
+				http.Error(w, "error adding a new user", http.StatusInternalServerError)
+			}
 			return
 		}
 		w.WriteHeader(http.StatusCreated)
-		w.Write([]byte("User created"))
+		w.Write([]byte("user created"))
 		return
 	}
 
diff --git a/auth/jwt.go b/internal/auth/jwt.go
similarity index 95%
rename from auth/jwt.go
rename to internal/auth/jwt.go
index 22b3a3f..c7bc391 100644
--- a/auth/jwt.go
+++ b/internal/auth/jwt.go
@@ -11,8 +11,8 @@ import (
 	"os"
 	"time"
 
-	"git.a71.su/Andrew71/pye/config"
-	"git.a71.su/Andrew71/pye/storage"
+	"git.a71.su/Andrew71/pye/internal/config"
+	"git.a71.su/Andrew71/pye/internal/models/user"
 	"github.com/golang-jwt/jwt/v5"
 )
 
@@ -66,7 +66,7 @@ func ServePublicKey(w http.ResponseWriter, r *http.Request) {
 }
 
 // Create creates a JSON Web Token that expires after a week
-func Create(user storage.User) (token string, err error) {
+func Create(user user.User) (token string, err error) {
 	t := jwt.NewWithClaims(jwt.SigningMethodRS256,
 		jwt.MapClaims{
 			"iss": "pye",
diff --git a/config/config.go b/internal/config/config.go
similarity index 100%
rename from config/config.go
rename to internal/config/config.go
diff --git a/logging/log.go b/internal/logging/log.go
similarity index 95%
rename from logging/log.go
rename to internal/logging/log.go
index 752c4e9..ec62790 100644
--- a/logging/log.go
+++ b/internal/logging/log.go
@@ -6,7 +6,7 @@ import (
 	"log/slog"
 	"os"
 
-	"git.a71.su/Andrew71/pye/config"
+	"git.a71.su/Andrew71/pye/internal/config"
 	"github.com/go-chi/chi/middleware"
 )
 
diff --git a/storage/user.go b/internal/models/user/user.go
similarity index 97%
rename from storage/user.go
rename to internal/models/user/user.go
index 52dc33f..cd18dea 100644
--- a/storage/user.go
+++ b/internal/models/user/user.go
@@ -1,4 +1,4 @@
-package storage
+package user
 
 import (
 	"log/slog"
diff --git a/storage/sqlite/sqlite.go b/internal/storage/sqlite/sqlite.go
similarity index 73%
rename from storage/sqlite/sqlite.go
rename to internal/storage/sqlite/sqlite.go
index e10ce79..da042c3 100644
--- a/storage/sqlite/sqlite.go
+++ b/internal/storage/sqlite/sqlite.go
@@ -3,11 +3,13 @@ package sqlite
 import (
 	"database/sql"
 	"errors"
+	"fmt"
 	"log/slog"
 	"os"
 
-	"git.a71.su/Andrew71/pye/storage"
-	_ "github.com/mattn/go-sqlite3"
+	"git.a71.su/Andrew71/pye/internal/models/user"
+	"git.a71.su/Andrew71/pye/internal/storage"
+	sqlite "github.com/mattn/go-sqlite3"
 )
 
 const create string = `
@@ -24,30 +26,36 @@ type SQLiteStorage struct {
 }
 
 func (s SQLiteStorage) Add(email, password string) error {
-	user, err := storage.New(email, password)
+	user, err := user.New(email, password)
 	if err != nil {
 		return err
 	}
 	_, err = s.db.Exec("insert into users (uuid, email, password) values ($1, $2, $3)",
 		user.Uuid.String(), user.Email, user.Hash)
 	if err != nil {
+		e, ok := err.(sqlite.Error)
+		if ok && errors.Is(e.ExtendedCode, sqlite.ErrConstraintUnique) {
+			// Return a standard error if the user already exists
+			slog.Info("can't add user because email already taken", "user", user)
+			return fmt.Errorf("%w (%s)", storage.ErrExist, user.Email)
+		}
 		slog.Error("error adding user to database", "error", err, "user", user)
 		return err
 	}
 	return nil
 }
 
-func (s SQLiteStorage) ById(uuid string) (storage.User, bool) {
+func (s SQLiteStorage) ById(uuid string) (user.User, bool) {
 	row := s.db.QueryRow("select * from users where uuid = $1", uuid)
-	user := storage.User{}
+	user := user.User{}
 	err := row.Scan(&user.Uuid, &user.Email, &user.Hash)
 
 	return user, err == nil
 }
 
-func (s SQLiteStorage) ByEmail(email string) (storage.User, bool) {
+func (s SQLiteStorage) ByEmail(email string) (user.User, bool) {
 	row := s.db.QueryRow("select * from users where email = $1", email)
-	user := storage.User{}
+	user := user.User{}
 	err := row.Scan(&user.Uuid, &user.Email, &user.Hash)
 
 	return user, err == nil
diff --git a/internal/storage/storage.go b/internal/storage/storage.go
new file mode 100644
index 0000000..d3cbada
--- /dev/null
+++ b/internal/storage/storage.go
@@ -0,0 +1,21 @@
+package storage
+
+import (
+	"errors"
+
+	"git.a71.su/Andrew71/pye/internal/models/user"
+)
+
+var ErrExist = errors.New("user already exists")
+
+// Storage is an interface for arbitrary storage
+type Storage interface {
+	Add(email, password string) error       // Add inserts a user into data
+	ById(uuid string) (user.User, bool)     // ById retrieves a user by their UUID
+	ByEmail(email string) (user.User, bool) // ByEmail retrieves a user by their email
+	Taken(email string) bool                // Taken checks whether an email is taken
+}
+
+// Data stores active information for the app.
+// It should be populated on startup
+var Data Storage
diff --git a/main.go b/main.go
index 957ff80..fc5cd60 100644
--- a/main.go
+++ b/main.go
@@ -1,7 +1,7 @@
 package main
 
-import "git.a71.su/Andrew71/pye/cmd"
+import "git.a71.su/Andrew71/pye/internal/app"
 
 func main() {
-	cmd.Execute()
+	app.Execute()
 }
diff --git a/storage/storage.go b/storage/storage.go
deleted file mode 100644
index c49feed..0000000
--- a/storage/storage.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package storage
-
-// Storage is an interface for arbitrary storage
-type Storage interface {
-	Add(email, password string) error  // Add inserts a user into data
-	ById(uuid string) (User, bool)     // ById retrieves a user by their UUID
-	ByEmail(email string) (User, bool) // ByEmail retrieves a user by their email
-	Taken(email string) bool           // Taken checks whether an email is taken
-}
-
-// Data stores active information for the app.
-// It should be populated on startup
-var Data Storage