diff --git a/ui/Puzzles.tsx b/ui/Puzzles.tsx
index 05dde48..ffa520e 100644
--- a/ui/Puzzles.tsx
+++ b/ui/Puzzles.tsx
@@ -497,7 +497,12 @@ function GroupForm({ chapter, token }: { chapter: Chapter; token: string }) {
                   type="text"
                   placeholder="Terre en vue mon capitaine !"
                   required
-                  {...register('name')}
+                  {...register('name', {
+                    pattern: {
+                      value: /^[a-zA-Z0-9À-ÿ\s_-]{3,20}$/,
+                      message: 'Le nom doit contenir entre 3 et 20 caractères'
+                    }
+                  })}
                 />
               </div>
             </>
diff --git a/ui/UserAuthForm.tsx b/ui/UserAuthForm.tsx
index ae8983d..78fea87 100644
--- a/ui/UserAuthForm.tsx
+++ b/ui/UserAuthForm.tsx
@@ -110,31 +110,51 @@ export default function UserAuthForm() {
             placeholder="philipzcwbarlow@peerat.dev"
             required
             error={errors.email?.message}
-            {...register('email')}
+            {...register('email', {
+              pattern: {
+                value: /^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$/,
+                message: 'Adresse e-mail invalide'
+              }
+            })}
           />
           <Input
             label="Nom"
             type="text"
             placeholder="Barlow"
             error={errors.lastname?.message}
-            {...register('lastname')}
+            {...register('lastname', {
+              pattern: {
+                value: /^[a-zA-ZÀ-ÿ]{3,20}$/,
+                message: '3 à 20 caractères alphabétiques'
+              }
+            })}
           />
           <Input
             label="Prénom"
             type="text"
             placeholder="Philipz"
             error={errors.firstname?.message}
-            {...register('firstname')}
+            {...register('firstname', {
+              pattern: {
+                value: /^[a-zA-ZÀ-ÿ]{3,20}$/,
+                message: '3 à 20 caractères alphabétiques'
+              }
+            })}
           />
         </>
       )}
       <Input
         label="Nom d'utilisateur"
         type="text"
-        placeholder="CW"
+        placeholder="Cypher Wolf"
         required
         error={errors.pseudo?.message}
-        {...register('pseudo')}
+        {...register('pseudo', {
+          pattern: {
+            value: /^[a-zA-Z0-9À-ÿ\s_-]{3,20}$/,
+            message: '3 à 20 caractères alphanumériques'
+          }
+        })}
       />
       <Input
         label="Mot de passe"