diff --git a/src/main/kotlin/com/oliver/kidio/backend/plugins/Routing.kt b/src/main/kotlin/com/oliver/kidio/backend/plugins/Routing.kt
index 0654cc5..8d55bc8 100644
--- a/src/main/kotlin/com/oliver/kidio/backend/plugins/Routing.kt
+++ b/src/main/kotlin/com/oliver/kidio/backend/plugins/Routing.kt
@@ -13,6 +13,25 @@ import io.ktor.server.routing.*
 import org.mindrot.jbcrypt.BCrypt
 import java.util.UUID
 
+fun isValidPassword(password: String): Boolean {
+    if (password.length < 8) return false
+
+    val hasUppercase = password.any { it.isUpperCase() }
+    val hasEmoji = password.any { char ->
+        val type = Character.getType(char).toByte()
+        type == Character.SURROGATE ||
+                type == Character.OTHER_SYMBOL ||
+                char.code in 0x1F600..0x1F64F ||
+                char.code in 0x1F300..0x1F5FF ||
+                char.code in 0x1F680..0x1F6FF ||
+                char.code in 0x2600..0x26FF
+    }
+
+    val hasSpecialChar = password.any { !it.isLetterOrDigit() && !hasEmoji }
+
+    return hasUppercase && hasSpecialChar && !hasEmoji
+}
+
 fun Application.configureRouting(repository: KidioRepository, jwtService : JwtService) {
     routing {
         post("/api/v1/auth/register") {
@@ -21,10 +40,17 @@ fun Application.configureRouting(repository: KidioRepository, jwtService : JwtSe
                 call.respond(HttpStatusCode.BadRequest, "Bitte füllen Sie alle Felder aus")
                 return@post
             }
+            if (!isValidPassword(registerRequest.passwordPlain)) {
+                call.respond(
+                    HttpStatusCode.BadRequest,
+                    "Das Passwort muss mindestens 8 Zeichen lang sein, mindestens einen Großbuchstaben und ein Sonderzeichen enthalten und darf keine Emojis enthalten."
+                )
+                return@post
+            }
             if (registerRequest.parentPin.length != 4) {
                 call.respond(HttpStatusCode.BadRequest, "Die Eltern-PIN muss genau 4 Ziffern lang sein")
                 return@post
-        }
+            }
             val existingUser = repository.findByEmail(registerRequest.email)
             if (existingUser != null) {
                 call.respond(HttpStatusCode.Conflict, "Ein Benutzer mit dieser E-Mail-Adresse existiert bereits")
diff --git a/src/test/kotlin/ServerTest.kt b/src/test/kotlin/ServerTest.kt
index 0acddd7..e71914c 100644
--- a/src/test/kotlin/ServerTest.kt
+++ b/src/test/kotlin/ServerTest.kt
@@ -71,7 +71,7 @@ class ServerTest {
             setBody(
                 """{
                     "email": "test@family.de",
-                    "passwordPlain": "strengGeheim1",
+                    "passwordPlain": "StrengGeheim1!",
                     "familyName": "Familie Schmidt",
                     "childAge": 8,
                     "parentPin": "4321"
@@ -87,7 +87,7 @@ class ServerTest {
             setBody(
                 """{
                     "email": "test@family.de",
-                    "passwordPlain": "strengGeheim1"
+                    "passwordPlain": "StrengGeheim1!"
                 }"""
             )
         }
@@ -97,6 +97,47 @@ class ServerTest {
         assertEquals("Familie Schmidt", loginJson.familyName)
     }
 
+    @Test
+    fun `test registration rejects invalid passwords`() = testApplication {
+        val jwtService = JwtService()
+        val repository = InMemoryKidioRepository()
+
+        application {
+            install(ServerContentNegotiation) {
+                json()
+            }
+            configureSecurity(jwtService)
+            configureRouting(repository, jwtService)
+        }
+
+        val invalidPasswords = listOf(
+            "Kurz1!",
+            "keingrossbuch1!",
+            "KeinSonder12",
+            "Passwort123!😊"
+        )
+
+        for (password in invalidPasswords) {
+            val response = client.post("/api/v1/auth/register") {
+                header(HttpHeaders.ContentType, ContentType.Application.Json.toString())
+                setBody(
+                    """{
+                        "email": "test_${System.currentTimeMillis()}@family.de",
+                        "passwordPlain": "$password",
+                        "familyName": "Familie Schmidt",
+                        "childAge": 8,
+                        "parentPin": "4321"
+                    }"""
+                )
+            }
+            assertEquals(
+                HttpStatusCode.BadRequest,
+                response.status,
+                "Passwort '$password' hätte abgelehnt werden müssen!"
+            )
+        }
+    }
+
     @Test
     fun `test tasks endpoint and verify with jwt`() = testApplication {
         val jwtService = JwtService()