diff --git a/lib/data/services/api_client.dart b/lib/data/services/api_client.dart
index 383f269..2d9e273 100644
--- a/lib/data/services/api_client.dart
+++ b/lib/data/services/api_client.dart
@@ -1,10 +1,10 @@
 import 'dart:convert';
-import 'dart:math';
 
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:http/http.dart';
+import 'package:logger/logger.dart';
 import 'package:seshat/config/constants.dart';
 import 'package:seshat/domain/models/accounting.dart';
 import 'package:seshat/domain/models/bal.dart';
@@ -22,8 +22,6 @@ extension StringExtension on String {
   }
 }
 
-typedef AuthHeaderProvider = String? Function();
-
 class ApiClient {
   ApiClient({String? host, int? port});
 
@@ -31,11 +29,17 @@ class ApiClient {
   String? token;
   bool isReady = false;
   FlutterSecureStorage? _secureStorage;
+  Logger log = Logger(
+    printer: PrettyPrinter(
+      colors: true,
+      lineLength: 100,
+      methodCount: 0,
+      dateTimeFormat: DateTimeFormat.dateAndTime,
+    ),
+  );
 
   Future<void> _initStore() async {
-    _secureStorage ??= const FlutterSecureStorage(
-      aOptions: AndroidOptions(encryptedSharedPreferences: true),
-    );
+    _secureStorage ??= const FlutterSecureStorage(aOptions: AndroidOptions());
   }
 
   Future<Map<String, String>> _getHeaders([
@@ -54,20 +58,25 @@ class ApiClient {
 */
 
   Future<Result<Accounting>> getAccounting(int balId) async {
+    final url = "https://$apiBasePath/bal/$balId/accounting";
+    log.i("Fetching: getAccounting ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders();
-      final response = await client.get(
-        Uri.parse("https://$apiBasePath/bal/$balId/accounting"),
-        headers: headers,
-      );
-      if (response.statusCode == 200) {
-        final json = jsonDecode(response.body);
-        return Result.ok(Accounting.fromJSON(json));
-      } else {
-        throw "Unknown error";
+      final response = await client.get(Uri.parse(url), headers: headers);
+      switch (response.statusCode) {
+        case 200:
+          final json = jsonDecode(response.body);
+          return Result.ok(Accounting.fromJSON(json));
+        case 403:
+          throw "You don't own the specified BAL";
+        case 404:
+          throw "No BAL with this is exists in database";
+        default:
+          throw "Unknown error of code ${response.statusCode.toString()}";
       }
     } catch (e) {
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -75,25 +84,32 @@ class ApiClient {
   }
 
   Future<Result<void>> returnToId(int balId, int ownerId, String type) async {
+    final url =
+        "https://$apiBasePath/bal/${balId.toString()}/accounting/return/${ownerId.toString()}";
+    log.i("Fetching: returnToId ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders({"Content-Type": "application/json"});
       final body = jsonEncode({"return_type": type.capitalize()});
-      debugPrint(body);
       final response = await client.post(
-        Uri.parse(
-          "https://$apiBasePath/bal/${balId.toString()}/accounting/return/${ownerId.toString()}",
-        ),
+        Uri.parse(url),
         headers: headers,
         body: body,
       );
-      if (response.statusCode == 200) {
-        return Result.ok(response);
-      } else {
-        throw "Unknown error ${response.statusCode.toString()}";
+      switch (response.statusCode) {
+        case 200:
+          return Result.ok(response);
+        case 403:
+          throw "You don't own the specified BAL or owner";
+        case 404:
+          throw "No BAL or owner with this id exists in database";
+        case 409:
+          throw "Books and money have already been returned, or there was nothing to return";
+        default:
+          throw "Unknown error of code ${response.statusCode.toString()}";
       }
     } catch (e) {
-      debugPrint(e.toString());
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -107,20 +123,27 @@ class ApiClient {
 */
 
   Future<Result<BalStats>> getBalStats(int id) async {
+    final url = "https://$apiBasePath/bal/${id.toString()}/stats";
+    log.i("Fetching: getBalStats ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders();
-      final response = await client.get(
-        Uri.parse("https://$apiBasePath/bal/${id.toString()}/stats"),
-        headers: headers,
-      );
-      if (response.statusCode == 200) {
-        final json = jsonDecode(response.body);
-        return Result.ok(BalStats.fromJSON(json));
-      } else {
-        throw "Unknown error";
+      final response = await client.get(Uri.parse(url), headers: headers);
+      switch (response.statusCode) {
+        case 200:
+          final json = jsonDecode(response.body);
+          return Result.ok(BalStats.fromJSON(json));
+        case 403:
+          throw "You don't own the specified BAL";
+        case 404:
+          throw "No BAL with this id exists in the database";
+        case 409:
+          throw "The specified BAL is not ended yet";
+        default:
+          throw "Unknown error with code ${response.statusCode.toString()}";
       }
     } catch (e) {
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -128,26 +151,27 @@ class ApiClient {
   }
 
   Future<Result<Bal>> stopBal(int id) async {
+    final url = "https://$apiBasePath/bal/${id.toString()}/stop";
+    log.i("Fetching: stopBal ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders();
-      final response = await client.post(
-        Uri.parse("https://$apiBasePath/bal/${id.toString()}/stop"),
-        headers: headers,
-      );
-      if (response.statusCode == 200) {
-        final json = jsonDecode(response.body);
-        return Result.ok(Bal.fromJSON(json));
-      } else if (response.statusCode == 403) {
-        throw "You don't own the specified BAL";
-      } else if (response.statusCode == 404) {
-        throw "No BAL with specified ID found";
-      } else if (response.statusCode == 409) {
-        throw "Selected BAL was not on ongoing state";
-      } else {
-        throw "Unknown error";
+      final response = await client.post(Uri.parse(url), headers: headers);
+      switch (response.statusCode) {
+        case 200:
+          final json = jsonDecode(response.body);
+          return Result.ok(Bal.fromJSON(json));
+        case 403:
+          throw "You don't own the specified BAL";
+        case 404:
+          throw "No BAL with specified ID found";
+        case 409:
+          throw "Selected BAL was not on ongoing state";
+        default:
+          throw "Unknown error with code ${response.statusCode.toString()}";
       }
     } catch (e) {
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -155,26 +179,27 @@ class ApiClient {
   }
 
   Future<Result<Bal>> startBal(int id) async {
+    final url = "https://$apiBasePath/bal/${id.toString()}/start";
+    log.i("Fetching: startBal ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders();
-      final response = await client.post(
-        Uri.parse("https://$apiBasePath/bal/${id.toString()}/start"),
-        headers: headers,
-      );
-      if (response.statusCode == 200) {
-        final json = jsonDecode(response.body);
-        return Result.ok(Bal.fromJSON(json));
-      } else if (response.statusCode == 403) {
-        throw "You don't own the specified BAL";
-      } else if (response.statusCode == 404) {
-        throw "No BAL with specified ID found";
-      } else if (response.statusCode == 409) {
-        throw "Cannot have multiple BAl ongoing at the same time!";
-      } else {
-        throw "Unknown error";
+      final response = await client.post(Uri.parse(url), headers: headers);
+      switch (response.statusCode) {
+        case 200:
+          final json = jsonDecode(response.body);
+          return Result.ok(Bal.fromJSON(json));
+        case 403:
+          throw "You don't own the specified BAL";
+        case 404:
+          throw "No BAL with specified ID found";
+        case 409:
+          throw "Cannot have multiple BAl ongoing at the same time!";
+        default:
+          throw "Unknown error with code ${response.statusCode.toString()}";
       }
     } catch (e) {
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -187,6 +212,8 @@ class ApiClient {
     DateTime start,
     DateTime end,
   ) async {
+    final url = "https://$apiBasePath/bal/${id.toString()}";
+    log.i("Fetching: editBal ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders({"Content-Type": "application/json"});
@@ -196,17 +223,23 @@ class ApiClient {
         "end_timestamp": (end.millisecondsSinceEpoch / 1000).round(),
       };
       final response = await client.patch(
-        Uri.parse("https://$apiBasePath/bal/${id.toString()}"),
+        Uri.parse(url),
         headers: headers,
         body: jsonEncode(body),
       );
-      if (response.statusCode == 200) {
-        final json = jsonDecode(response.body);
-        return Result.ok(Bal.fromJSON(json));
-      } else {
-        throw Exception("Something went wrong");
+      switch (response.statusCode) {
+        case 200:
+          final json = jsonDecode(response.body);
+          return Result.ok(Bal.fromJSON(json));
+        case 403:
+          throw "You don't own the specified BAL";
+        case 404:
+          throw "No bal with specified id";
+        default:
+          throw "Unknown error with code ${response.statusCode.toString()}";
       }
     } catch (e) {
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -214,24 +247,25 @@ class ApiClient {
   }
 
   Future<Result<Bal>> getBalById(int id) async {
+    final url = "https://$apiBasePath/bal/${id.toString()}";
+    log.i("Fetching: getBalById ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders();
-      final response = await client.get(
-        Uri.parse("https://$apiBasePath/bal/${id.toString()}"),
-        headers: headers,
-      );
-      if (response.statusCode == 200) {
-        final json = jsonDecode(response.body);
-        return Result.ok(Bal.fromJSON(json));
-      } else if (response.statusCode == 403) {
-        throw Exception("You don't own the specified bal");
-      } else {
-        return Result.error(
-          Exception("No bal wirth this id exists the database"),
-        );
+      final response = await client.get(Uri.parse(url), headers: headers);
+      switch (response.statusCode) {
+        case 200:
+          final json = jsonDecode(response.body);
+          return Result.ok(Bal.fromJSON(json));
+        case 403:
+          throw "You don't own the specified BAL";
+        case 404:
+          throw "No BAL with this id found in database";
+        default:
+          throw "Unknown error";
       }
     } catch (e) {
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -239,6 +273,8 @@ class ApiClient {
   }
 
   Future<Result<Bal>> addBal(String name, DateTime start, DateTime end) async {
+    final url = "https://$apiBasePath/bal";
+    log.i("Fetching: addBal ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders({"Content-Type": "application/json"});
@@ -248,17 +284,21 @@ class ApiClient {
         "end_timestamp": (end.millisecondsSinceEpoch / 1000).round(),
       };
       final response = await client.post(
-        Uri.parse("https://$apiBasePath/bal"),
+        Uri.parse(url),
         headers: headers,
         body: jsonEncode(body),
       );
-      if (response.statusCode == 201) {
-        final json = jsonDecode(response.body);
-        return Result.ok(Bal.fromJSON(json));
-      } else {
-        throw Exception("Something went wrong");
+      switch (response.statusCode) {
+        case 201:
+          final json = jsonDecode(response.body);
+          return Result.ok(Bal.fromJSON(json));
+        case 400:
+          throw "Time cannot go backwards";
+        default:
+          throw "Unknown error with code ${response.statusCode.toString()}";
       }
     } catch (e) {
+      log.e(e.toString());
       return Result.error(Exception(e));
     } finally {
       client.close();
@@ -266,20 +306,14 @@ class ApiClient {
   }
 
   Future<Result<List<Bal>>> getBals() async {
+    final url = "https://$apiBasePath/bals";
+    log.i("Fetching: getBals ($url)");
     final client = Client();
     try {
       final headers = await _getHeaders();
-      final response = await client.get(
-        Uri.parse("https://$apiBasePath/bals"),
-        headers: headers,
-      );
+      final response = await client.get(Uri.parse(url), headers: headers);
       if (response.statusCode == 200) {
         final json = jsonDecode(response.body) as List<dynamic>;
-        debugPrint("\n\n\n\nRECEIVED : $json\n\n\n\n");
-        debugPrint(
-          "\n\n\n\nFORMATTED : ${json.map((element) => Bal.fromJSON(element)).toList()}\n\n\n\n",
-        );
-
         return Result.ok(json.map((element) => Bal.fromJSON(element)).toList());
       } else {
         throw Exception("Something wrong happened");
diff --git a/lib/ui/add_page/widgets/confirmation_popup.dart b/lib/ui/add_page/widgets/confirmation_popup.dart
index f026ad6..6a6ca74 100644
--- a/lib/ui/add_page/widgets/confirmation_popup.dart
+++ b/lib/ui/add_page/widgets/confirmation_popup.dart
@@ -1,3 +1,5 @@
+import 'dart:nativewrappers/_internal/vm/lib/ffi_patch.dart';
+
 import 'package:flutter/material.dart';
 import 'package:seshat/domain/models/book.dart';
 import 'package:seshat/ui/add_page/view_model/add_view_model.dart';
@@ -80,12 +82,16 @@ class _ConfirmationPopupState extends State<ConfirmationPopup> {
                         border: OutlineInputBorder(),
                         suffixText: "€",
                       ),
-                      keyboardType: TextInputType.number,
+                      keyboardType: TextInputType.numberWithOptions(
+                        decimal: true,
+                      ),
                       validator: (value) {
                         if (value == null || value.isEmpty) {
                           return "Indiquez un prix";
                         } else if (num.tryParse(value) == null) {
                           return "Le prix doit être un nombre";
+                        } else if (num.parse(value) < 0) {
+                          return "Le prix doit être positif ou nul";
                         }
                         return null;
                       },
diff --git a/lib/ui/add_page/widgets/form_popup.dart b/lib/ui/add_page/widgets/form_popup.dart
index 7f6af10..59368e0 100644
--- a/lib/ui/add_page/widgets/form_popup.dart
+++ b/lib/ui/add_page/widgets/form_popup.dart
@@ -145,12 +145,16 @@ class _ManualEANPopupState extends State<_ManualEANPopup> {
                           border: OutlineInputBorder(),
                           suffixText: "€",
                         ),
-                        keyboardType: TextInputType.number,
+                        keyboardType: TextInputType.numberWithOptions(
+                          decimal: true,
+                        ),
                         validator: (value) {
                           if (value == null || value.isEmpty) {
                             return "Indiquez un prix";
                           } else if (num.tryParse(value) == null) {
                             return "Le prix doit être un nombre";
+                          } else if (num.parse(value) < 0) {
+                            return "Le prix doit être positif ou nul";
                           }
                           return null;
                         },
@@ -273,12 +277,16 @@ class _FullyManualState extends State<_FullyManual> {
                           border: OutlineInputBorder(),
                           suffixText: "€",
                         ),
-                        keyboardType: TextInputType.number,
+                        keyboardType: TextInputType.numberWithOptions(
+                          decimal: true,
+                        ),
                         validator: (value) {
                           if (value == null || value.isEmpty) {
                             return "Indiquez un prix";
                           } else if (num.tryParse(value) == null) {
                             return "Le prix doit être un nombre";
+                          } else if (num.parse(value) < 0) {
+                            return "Le prix doit être positif ou nul";
                           }
                           return null;
                         },
diff --git a/lib/ui/sell_page/widgets/sell_page.dart b/lib/ui/sell_page/widgets/sell_page.dart
index 46b2938..dd0404b 100644
--- a/lib/ui/sell_page/widgets/sell_page.dart
+++ b/lib/ui/sell_page/widgets/sell_page.dart
@@ -129,7 +129,9 @@ class _SellPageState extends State<SellPage> {
                                 suffixText: "€",
                                 border: OutlineInputBorder(),
                               ),
-                              keyboardType: TextInputType.number,
+                              keyboardType: TextInputType.numberWithOptions(
+                                decimal: true,
+                              ),
                             ),
                           ),
                         ),
diff --git a/pubspec.lock b/pubspec.lock
index 97d2e53..39a3563 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -293,8 +293,16 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "5.1.1"
-  logging:
+  logger:
     dependency: "direct main"
+    description:
+      name: logger
+      sha256: "55d6c23a6c15db14920e037fe7e0dc32e7cdaf3b64b4b25df2d541b5b6b81c0c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.6.1"
+  logging:
+    dependency: transitive
     description:
       name: logging
       sha256: c8245ada5f1717ed44271ed1c26b8ce85ca3228fd2ffdb75468ab01979309d61
diff --git a/pubspec.yaml b/pubspec.yaml
index 2c18afe..fc17ee5 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -41,7 +41,6 @@ dependencies:
   provider: ^6.1.5
   flutter_svg: ^2.2.0
   go_router: ^16.0.0
-  logging: ^1.3.0
   http: ^1.4.0
   web_socket_channel: ^3.0.3
   nested: ^1.0.0
@@ -51,6 +50,7 @@ dependencies:
   intl: ^0.20.2
   flutter_launcher_icons: ^0.14.4
   fl_chart: ^1.0.0
+  logger: ^2.6.1
 
 dev_dependencies:
   flutter_test: