diff --git a/src/components/device-management/device-management.ts b/src/components/device-management/device-management.ts
index 6d1d351..e30bd60 100644
--- a/src/components/device-management/device-management.ts
+++ b/src/components/device-management/device-management.ts
@@ -649,8 +649,8 @@ export class DeviceManagementComponent extends HTMLElement {
         if (file) {
           try {
             const text = await file.text();
-            const data = JSON.parse(text);
-            // Use data variable
+            const _data = JSON.parse(text);
+            // Data parsed but not used yet (for future use)
 
             // Import the account data
             if (window.importJSON) {
diff --git a/src/components/login-modal/login-modal.js b/src/components/login-modal/login-modal.js
index 27f96d6..0ef06b5 100755
--- a/src/components/login-modal/login-modal.js
+++ b/src/components/login-modal/login-modal.js
@@ -9,5 +9,7 @@ export async function closeLoginModal() {
   router.closeLoginModal();
 }
 
+/* eslint-disable no-undef */
 window.confirmLogin = confirmLogin;
 window.closeLoginModal = closeLoginModal;
+/* eslint-enable no-undef */
diff --git a/src/components/secure-credentials/secure-credentials.ts b/src/components/secure-credentials/secure-credentials.ts
index b0523c7..32e9c78 100644
--- a/src/components/secure-credentials/secure-credentials.ts
+++ b/src/components/secure-credentials/secure-credentials.ts
@@ -232,7 +232,7 @@ export class SecureCredentialsComponent {
     try {
       await this.updateUI();
       this.showMessage('Credentials actualisés', 'success');
-    } catch (error) {
+    } catch (_error) {
       this.showMessage('Erreur lors de l\'actualisation', 'error');
     }
   }
diff --git a/src/components/security-mode-selector/security-mode-selector.ts b/src/components/security-mode-selector/security-mode-selector.ts
index b95abb2..de27363 100644
--- a/src/components/security-mode-selector/security-mode-selector.ts
+++ b/src/components/security-mode-selector/security-mode-selector.ts
@@ -17,12 +17,12 @@ export interface SecurityModeConfig {
 export class SecurityModeSelector {
   private container: HTMLElement;
   private selectedMode: SecurityMode | null = null;
-  private onModeSelected: (mode: SecurityMode) => void;
+  private onModeSelected: (_mode: SecurityMode) => void;
   private onCancel: () => void;
 
   constructor(
     container: HTMLElement,
-    onModeSelected: (mode: SecurityMode) => void,
+    onModeSelected: (_mode: SecurityMode) => void,
     onCancel: () => void
   ) {
     this.container = container;
diff --git a/src/pages/birthday-setup/birthday-setup.ts b/src/pages/birthday-setup/birthday-setup.ts
index 9247308..7c512b2 100644
--- a/src/pages/birthday-setup/birthday-setup.ts
+++ b/src/pages/birthday-setup/birthday-setup.ts
@@ -105,7 +105,7 @@ document.addEventListener('DOMContentLoaded', async () => {
                 }
             }
             // Vérifier que le wallet contient bien les données attendues
-            if (wallet.sp_wallet && wallet.sp_wallet.birthday !== undefined) {
+            if (wallet.sp_wallet?.birthday !== undefined) {
                 console.log('✅ Wallet found in database with birthday:', wallet.sp_wallet.birthday);
             } else {
                 throw new Error('Wallet found but missing required data (sp_wallet or birthday)');
diff --git a/src/pages/block-sync/block-sync.ts b/src/pages/block-sync/block-sync.ts
index a2631cf..b02d68e 100644
--- a/src/pages/block-sync/block-sync.ts
+++ b/src/pages/block-sync/block-sync.ts
@@ -141,7 +141,7 @@ document.addEventListener("DOMContentLoaded", async () => {
         }
 
         // Vérifier que le wallet contient bien les données attendues
-        if (wallet.sp_wallet && wallet.sp_wallet.birthday !== undefined) {
+        if (wallet.sp_wallet?.birthday !== undefined) {
             console.log('✅ Wallet found in database with birthday:', wallet.sp_wallet.birthday);
         } else {
             throw new Error('Wallet found but missing required data (sp_wallet or birthday)');
diff --git a/src/pages/home/home.ts b/src/pages/home/home.ts
index 8f84494..59372b0 100755
--- a/src/pages/home/home.ts
+++ b/src/pages/home/home.ts
@@ -91,7 +91,7 @@ export async function initHomePage(): Promise<void> {
     }
 
     // Vérifier que le wallet contient bien les données attendues
-    if (wallet.sp_wallet && wallet.sp_wallet.birthday !== undefined) {
+    if (wallet.sp_wallet?.birthday !== undefined) {
       console.log('✅ Wallet found in database with birthday:', wallet.sp_wallet.birthday);
     } else {
       throw new Error('Wallet found but missing required data (sp_wallet or birthday)');
diff --git a/src/router.ts b/src/router.ts
index e02436d..1419390 100755
--- a/src/router.ts
+++ b/src/router.ts
@@ -49,14 +49,14 @@ export async function checkStorageStateAndNavigate(): Promise<void> {
 
     // Vérifier si la date anniversaire est configurée (wallet avec birthday > 0)
     const device = await services.getDeviceFromDatabase();
-    if (device && device.sp_wallet && device.sp_wallet.birthday > 0) {
+    if (device?.sp_wallet && device.sp_wallet.birthday > 0) {
       console.log('🎂 Birthday is configured, navigating to pairing');
       await navigate('home'); // Pour l'instant, rediriger vers home pour le pairing
       return;
     }
 
     // Vérifier si le wallet existe (même avec birthday = 0)
-    if (device && device.sp_wallet) {
+    if (device?.sp_wallet) {
       console.log('💰 Wallet exists but birthday not set, navigating to birthday-setup');
       await navigate('birthday-setup');
       return;
@@ -1255,7 +1255,7 @@ async function handleSecurityKeyManagement(): Promise<boolean> {
 /**
  * ÉTAPE 5: Handshake
  */
-async function performHandshake(services: any): Promise<void> {
+async function performHandshake(_services: any): Promise<void> {
   console.log('🤝 Performing handshake...');
 
   try {
diff --git a/src/services/credentials/encryption.service.ts b/src/services/credentials/encryption.service.ts
index c514211..0ac8421 100644
--- a/src/services/credentials/encryption.service.ts
+++ b/src/services/credentials/encryption.service.ts
@@ -90,10 +90,9 @@ export class EncryptionService {
 
       return btoa(String.fromCharCode(...combined));
     } catch (error) {
-      secureLogger.error('Failed to encrypt with password', {
+      secureLogger.error('Failed to encrypt with password', error as Error, {
         component: 'EncryptionService',
-        operation: 'encryptWithPassword',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'encryptWithPassword'
       });
       throw error;
     }
@@ -206,10 +205,9 @@ export class EncryptionService {
 
       return new TextDecoder().decode(decrypted);
     } catch (error) {
-      secureLogger.error('Failed to decrypt with password base64', {
+      secureLogger.error('Failed to decrypt with password base64', error as Error, {
         component: 'EncryptionService',
-        operation: 'decryptWithPasswordBase64',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'decryptWithPasswordBase64'
       });
       throw error;
     }
@@ -236,7 +234,7 @@ export class EncryptionService {
     const key = await crypto.subtle.deriveKey(
       {
         name: 'PBKDF2',
-        salt: salt,
+        salt: new Uint8Array(salt),
         iterations: iterations,
         hash: 'SHA-256'
       },
diff --git a/src/services/credentials/storage.service.ts b/src/services/credentials/storage.service.ts
index d722711..2e7b488 100644
--- a/src/services/credentials/storage.service.ts
+++ b/src/services/credentials/storage.service.ts
@@ -103,8 +103,7 @@ export class StorageService {
   async hasCredentials(): Promise<boolean> {
     try {
       const credentials = await this.getCredentials();
-      return credentials !== null &&
-             credentials.spendKey !== undefined &&
+      return credentials?.spendKey !== undefined &&
              credentials.scanKey !== undefined;
     } catch (error) {
       secureLogger.error('Failed to check credentials existence', error as Error, {
diff --git a/src/services/credentials/webauthn.service.ts b/src/services/credentials/webauthn.service.ts
index b04c0f8..6943893 100644
--- a/src/services/credentials/webauthn.service.ts
+++ b/src/services/credentials/webauthn.service.ts
@@ -59,7 +59,7 @@ export class WebAuthnService {
    */
   async detectAvailableAuthenticators(): Promise<boolean> {
     try {
-      if (!navigator.credentials || !navigator.credentials.create) {
+      if (!navigator.credentials?.create) {
         return false;
       }
 
@@ -105,7 +105,7 @@ export class WebAuthnService {
 
       // Vérifier la disponibilité sans faire d'appel réel à WebAuthn
       // Juste vérifier que les APIs sont disponibles
-      if (!navigator.credentials || !navigator.credentials.create) {
+      if (!navigator.credentials?.create) {
         console.log('❌ WebAuthn credentials API not available');
         return false;
       }
diff --git a/src/services/database.service.ts b/src/services/database.service.ts
index 159de61..2347177 100755
--- a/src/services/database.service.ts
+++ b/src/services/database.service.ts
@@ -79,7 +79,7 @@ export class Database {
 
         Object.values(this.storeDefinitions).forEach(({ name, options, indices }) => {
           if (!db.objectStoreNames.contains(name)) {
-            let store = db.createObjectStore(name, options as IDBObjectStoreParameters);
+            const store = db.createObjectStore(name, options as IDBObjectStoreParameters);
 
             indices.forEach(({ name, keyPath, options }) => {
               store.createIndex(name, keyPath, options);
@@ -116,7 +116,7 @@ export class Database {
   }
 
   public async registerServiceWorker(path: string) {
-    if (!('serviceWorker' in navigator)) return; // Ensure service workers are supported
+    if (!('serviceWorker' in navigator)) {return;} // Ensure service workers are supported
     console.log('registering worker at', path);
 
     try {
@@ -268,7 +268,7 @@ export class Database {
 
   private async handleDownloadList(downloadList: string[]): Promise<void> {
     // Download the missing data
-    let requestedStateId: string[] = [];
+    const requestedStateId: string[] = [];
     const service = await Services.getInstance();
     for (const hash of downloadList) {
       const diff = await service.getDiffByValue(hash);
@@ -321,7 +321,7 @@ export class Database {
     } else if (data.type === 'TO_DOWNLOAD') {
       console.log(`Received missing data ${data}`);
       // Download the missing data
-      let requestedStateId: string[] = [];
+      const requestedStateId: string[] = [];
       for (const hash of data.data) {
         try {
           const valueBytes = await service.fetchValueFromStorage(hash);
diff --git a/src/services/secure-credentials.service.ts b/src/services/secure-credentials.service.ts
index 1b0ab74..b76036c 100644
--- a/src/services/secure-credentials.service.ts
+++ b/src/services/secure-credentials.service.ts
@@ -128,10 +128,9 @@ export class SecureCredentialsService {
           return false;
       }
     } catch (error) {
-      secureLogger.error('Failed to check PBKDF2 key existence', {
+      secureLogger.error('Failed to check PBKDF2 key existence', error as Error, {
         component: 'SecureCredentialsService',
-        operation: 'hasPBKDF2Key',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'hasPBKDF2Key'
       });
       return false;
     }
@@ -155,10 +154,9 @@ export class SecureCredentialsService {
 
       return result;
     } catch (error) {
-      secureLogger.error('Failed to retrieve PBKDF2 key from pbkdf2keys store', {
+      secureLogger.error('Failed to retrieve PBKDF2 key from pbkdf2keys store', error as Error, {
         component: 'SecureCredentialsService',
-        operation: 'getPBKDF2KeyFromStore',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'getPBKDF2KeyFromStore'
       });
       return null;
     }
@@ -186,10 +184,9 @@ export class SecureCredentialsService {
         securityMode
       });
     } catch (error) {
-      secureLogger.error('Failed to store PBKDF2 key in pbkdf2keys store', {
+      secureLogger.error('Failed to store PBKDF2 key in pbkdf2keys store', error as Error, {
         component: 'SecureCredentialsService',
-        operation: 'storePBKDF2KeyInStore',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'storePBKDF2KeyInStore'
       });
       throw error;
     }
@@ -238,10 +235,9 @@ export class SecureCredentialsService {
           return null;
       }
     } catch (error) {
-      secureLogger.error('Failed to retrieve PBKDF2 key', {
+      secureLogger.error('Failed to retrieve PBKDF2 key', error as Error, {
         component: 'SecureCredentialsService',
-        operation: 'retrievePBKDF2Key',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'retrievePBKDF2Key'
       });
       return null;
     }
@@ -325,10 +321,9 @@ export class SecureCredentialsService {
       return pbkdf2Key;
 
     } catch (error) {
-      secureLogger.error('Failed to generate PBKDF2 key', {
+      secureLogger.error('Failed to generate PBKDF2 key', error as Error, {
         component: 'SecureCredentialsService',
-        operation: 'generatePBKDF2Key',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'generatePBKDF2Key'
       });
       throw error;
     }
@@ -492,7 +487,7 @@ export class SecureCredentialsService {
    * Génère des credentials en clair
    */
   private async generatePlainCredentials(
-    password: string,
+    _password: string,
     _options: CredentialOptions = {}
   ): Promise<CredentialData> {
     try {
@@ -575,7 +570,7 @@ export class SecureCredentialsService {
    */
   private async decryptWithWebAuthn(
     credentials: CredentialData,
-    password: string
+    _password: string
   ): Promise<CredentialData> {
     try {
       const currentMode = await this.securityModeService.getCurrentMode();
@@ -647,7 +642,7 @@ export class SecureCredentialsService {
   /**
    * Stocke des credentials
    */
-  async storeCredentials(credentials: CredentialData, password: string): Promise<void> {
+  async storeCredentials(credentials: CredentialData, _password: string): Promise<void> {
     try {
       // Import dynamique du service de stockage
       const { StorageService } = await import('./credentials/storage.service');
@@ -713,7 +708,7 @@ export class SecureCredentialsService {
   /**
    * Valide un code OTP
    */
-  async validateOTPCode(secret: string, code: string): Promise<boolean> {
+  async validateOTPCode(_secret: string, code: string): Promise<boolean> {
     try {
       // Implémentation simplifiée de validation OTP
       // Dans une implémentation complète, on utiliserait une bibliothèque comme speakeasy
@@ -950,12 +945,14 @@ QR Code URL: ${qrUrl}`);
     try {
       // Essayer de récupérer un mot de passe existant
       const existingCredential = await navigator.credentials.get({
+        // @ts-expect-error - PasswordCredential API may not be in TypeScript definitions
         password: true,
         mediation: 'optional'
-      });
+      } as CredentialRequestOptions);
 
-      if (existingCredential && existingCredential.type === 'password') {
-        const passwordCredential = existingCredential as PasswordCredential;
+      if (existingCredential?.type === 'password') {
+        // @ts-expect-error - PasswordCredential API may not be in TypeScript definitions
+        const passwordCredential = existingCredential as any;
         console.log('🔐 Retrieved existing password from browser');
         return passwordCredential.password;
       }
@@ -1035,7 +1032,9 @@ QR Code URL: ${qrUrl}`);
 
         try {
           // Sauvegarder le mot de passe dans le gestionnaire de mots de passe du navigateur
-          if (navigator.credentials && navigator.credentials.create) {
+          // @ts-expect-error - PasswordCredential API may not be in TypeScript definitions
+          if (typeof PasswordCredential !== 'undefined' && navigator.credentials && navigator.credentials.create) {
+            // @ts-expect-error - PasswordCredential API may not be in TypeScript definitions
             const credential = new PasswordCredential({
               id: '4nk-pbkdf2-password',
               password: password,
@@ -1097,10 +1096,9 @@ QR Code URL: ${qrUrl}`);
       const encryptionService = EncryptionService.getInstance();
       return await encryptionService.decrypt(encryptedKey, password);
     } catch (error) {
-      secureLogger.error('Failed to decrypt PBKDF2 key with password', {
+      secureLogger.error('Failed to decrypt PBKDF2 key with password', error as Error, {
         component: 'SecureCredentialsService',
-        operation: 'decryptPBKDF2KeyWithPassword',
-        error: error instanceof Error ? error.message : String(error)
+        operation: 'decryptPBKDF2KeyWithPassword'
       });
       return null;
     }
@@ -1118,12 +1116,14 @@ QR Code URL: ${qrUrl}`);
 
     try {
       const credential = await navigator.credentials.get({
+        // @ts-expect-error - PasswordCredential API may not be in TypeScript definitions
         password: true,
         mediation: 'optional'
-      });
+      } as CredentialRequestOptions);
 
-      if (credential && credential.type === 'password') {
-        const passwordCredential = credential as PasswordCredential;
+      if (credential?.type === 'password') {
+        // @ts-expect-error - PasswordCredential API may not be in TypeScript definitions
+        const passwordCredential = credential as any;
         console.log('🔐 Retrieved password from browser password manager');
         return passwordCredential.password;
       }
@@ -1151,14 +1151,14 @@ QR Code URL: ${qrUrl}`);
       return { isValid: false, score: 0, feedback };
     }
 
-    if (password.length >= 8) score += 1;
-    if (password.length >= 12) score += 1;
-    if (password.length >= 16) score += 1;
+    if (password.length >= 8) {score += 1;}
+    if (password.length >= 12) {score += 1;}
+    if (password.length >= 16) {score += 1;}
 
-    if (/[a-z]/.test(password)) score += 1;
-    if (/[A-Z]/.test(password)) score += 1;
-    if (/[0-9]/.test(password)) score += 1;
-    if (/[^a-zA-Z0-9]/.test(password)) score += 1;
+    if (/[a-z]/.test(password)) {score += 1;}
+    if (/[A-Z]/.test(password)) {score += 1;}
+    if (/[0-9]/.test(password)) {score += 1;}
+    if (/[^a-zA-Z0-9]/.test(password)) {score += 1;}
 
     // Feedback détaillé
     if (score < 3) {
diff --git a/src/services/security-mode.service.ts b/src/services/security-mode.service.ts
index 5f20d79..92784bf 100644
--- a/src/services/security-mode.service.ts
+++ b/src/services/security-mode.service.ts
@@ -5,6 +5,7 @@
  */
 
 import { secureLogger } from './secure-logger';
+import Database from './database.service';
 
 export type SecurityMode = 'proton-pass' | 'os' | 'otp' | '2fa' | 'password' | 'none';
 
diff --git a/src/services/service.ts b/src/services/service.ts
index 49c23a8..d1ae0eb 100755
--- a/src/services/service.ts
+++ b/src/services/service.ts
@@ -1328,7 +1328,7 @@ export default class Services {
             console.log(`💰 Amount after block scan: ${updatedAmount}`);
 
             // Update user with scan results
-            if (updatedAmount > BigInt(0)) {
+            if (updatedAmount > 0n) {
               this.updateUserStatus(`💰 Wallet updated! Found ${updatedAmount} tokens`);
             } else {
               this.updateUserStatus('⏳ Transaction processed, waiting for confirmation...');
@@ -1887,7 +1887,7 @@ export default class Services {
         getRequest.onerror = () => reject(getRequest.error);
       });
 
-      if (walletData && walletData.encrypted_wallet) {
+      if (walletData?.encrypted_wallet) {
         encryptedWallet = walletData.encrypted_wallet;
         console.log('✅ encrypted_wallet preserved');
       } else {
@@ -1941,7 +1941,7 @@ export default class Services {
             await new Promise<void>((resolveVerify, rejectVerify) => {
               verifyRequest.onsuccess = () => {
                 const savedData = verifyRequest.result;
-                if (savedData && savedData.encrypted_device === encryptedDevice) {
+                if (savedData?.encrypted_device === encryptedDevice) {
                   console.log('✅ Verified: Device correctly saved in database');
                   resolveVerify();
                 } else {