diff --git a/simulator-ui/src/main.tsx b/simulator-ui/src/main.tsx
index abd961e..94e467c 100644
--- a/simulator-ui/src/main.tsx
+++ b/simulator-ui/src/main.tsx
@@ -30,58 +30,65 @@ type LogEntry = {
   createdAt: string;
 };
 
-const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || window.location.origin;
+type Language = "en" | "fr";
+type Translation = {
+  en: string;
+  fr: string;
+};
 
-const scenarios: Array<{ key: ScenarioKey; title: string; description: string }> = [
+const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || window.location.origin;
+const LANGUAGE_STORAGE_KEY = "plast-track-simulator-language";
+
+const scenarios: Array<{ key: ScenarioKey; title: Translation; description: Translation }> = [
   {
     key: "power_on",
-    title: "Power ON",
-    description: "Simulate machine power available.",
+    title: { en: "Power ON", fr: "Marche ON" },
+    description: { en: "Simulate machine power available.", fr: "Simuler la presence alimentation machine." },
   },
   {
     key: "power_off",
-    title: "Power OFF",
-    description: "Close open downtime and move out of planning.",
+    title: { en: "Power OFF", fr: "Arret OFF" },
+    description: { en: "Close open downtime and move out of planning.", fr: "Fermer l'arret ouvert et sortir du planning." },
   },
   {
     key: "cycle_completed",
-    title: "Single Cycle",
-    description: "Publish one normalized completed cycle.",
+    title: { en: "Single Cycle", fr: "Cycle simple" },
+    description: { en: "Publish one normalized completed cycle.", fr: "Publier un cycle termine normalise." },
   },
   {
     key: "cycle_burst",
-    title: "Cycle Burst",
-    description: "Generate many cycles with the selected cycle time.",
+    title: { en: "Cycle Burst", fr: "Rafale cycles" },
+    description: { en: "Generate many cycles with the selected cycle time.", fr: "Generer plusieurs cycles avec le temps choisi." },
   },
   {
     key: "cycle_signal_edge",
-    title: "Passive Edge",
-    description: "Toggle cycle_signal using the machine configured edge.",
+    title: { en: "Passive Edge", fr: "Front passif" },
+    description: { en: "Toggle cycle_signal using the machine configured edge.", fr: "Basculer cycle_signal selon le front configure." },
   },
   {
     key: "debounce_noise",
-    title: "Debounce Noise",
-    description: "Send a too-fast edge that should be ignored.",
+    title: { en: "Debounce Noise", fr: "Bruit anti-rebond" },
+    description: { en: "Send a too-fast edge that should be ignored.", fr: "Envoyer un front trop rapide qui doit etre ignore." },
   },
   {
     key: "machine_stopped",
-    title: "Open Stop",
-    description: "Force an unqualified downtime if an OF is running.",
+    title: { en: "Open Stop", fr: "Ouvrir arret" },
+    description: { en: "Force an unqualified downtime if an OF is running.", fr: "Forcer un arret non qualifie si un OF est en cours." },
   },
   {
     key: "recover_with_cycle",
-    title: "Recover",
-    description: "Close downtime by producing a new cycle.",
+    title: { en: "Recover", fr: "Reprise" },
+    description: { en: "Close downtime by producing a new cycle.", fr: "Fermer l'arret avec un nouveau cycle." },
   },
   {
     key: "alarm_on",
-    title: "Alarm ON",
-    description: "Raise the general_alarm passive signal.",
+    title: { en: "Alarm ON", fr: "Alarme ON" },
+    description: { en: "Raise the general_alarm passive signal.", fr: "Activer le signal passif general_alarm." },
   },
   {
     key: "alarm_off",
-    title: "Alarm OFF",
-    description: "Clear the general_alarm passive signal.",
+    title: { en: "Alarm OFF", fr: "Alarme OFF" },
+    description: { en: "Clear the general_alarm passive signal.", fr: "Desactiver le signal passif general_alarm." },
   },
 ];
 
@@ -113,6 +120,10 @@ function parseInputValue(value: string): boolean | number | string {
 }
 
 function App() {
+  const [language, setLanguage] = useState<Language>(() => {
+    const savedLanguage = localStorage.getItem(LANGUAGE_STORAGE_KEY);
+    return savedLanguage === "en" || savedLanguage === "fr" ? savedLanguage : "fr";
+  });
   const [machines, setMachines] = useState<Machine[]>([]);
   const [selectedMachine, setSelectedMachine] = useState("");
   const [cycleTimeSec, setCycleTimeSec] = useState(20);
@@ -122,15 +133,27 @@ function App() {
   const [loading, setLoading] = useState(false);
   const [logs, setLogs] = useState<LogEntry[]>([]);
 
+  function t(en: string, fr: string) {
+    return language === "fr" ? fr : en;
+  }
+
+  function tt(value: Translation) {
+    return value[language];
+  }
+
   useEffect(() => {
     apiRequest<Machine[]>("/api/machines")
       .then((items) => {
         setMachines(items);
         setSelectedMachine((current) => current || items[0]?.code || "");
       })
-      .catch((error: Error) => addLog("Load machines", "error", error.message));
+      .catch((error: Error) => addLog(t("Load machines", "Chargement machines"), "error", error.message));
   }, []);
 
+  useEffect(() => {
+    localStorage.setItem(LANGUAGE_STORAGE_KEY, language);
+  }, [language]);
+
   function addLog(label: string, status: LogEntry["status"], details: string) {
     setLogs((current) => [
       {
@@ -146,7 +169,7 @@ function App() {
 
   async function runScenario(scenario: ScenarioKey) {
     if (!selectedMachine) {
-      addLog("Scenario blocked", "error", "Select a machine first.");
+      addLog(t("Scenario blocked", "Scenario bloque"), "error", t("Select a machine first.", "Selectionner une machine d'abord."));
       return;
     }
     setLoading(true);
@@ -160,9 +183,10 @@ function App() {
           count: burstCount,
         }),
       });
-      addLog(scenario, "ok", JSON.stringify(result, null, 2));
+      const scenarioLabel = scenarios.find((item) => item.key === scenario)?.title;
+      addLog(scenarioLabel ? tt(scenarioLabel) : scenario, "ok", JSON.stringify(result, null, 2));
     } catch (error) {
-      addLog(scenario, "error", error instanceof Error ? error.message : "Unknown error");
+      addLog(scenario, "error", error instanceof Error ? error.message : t("Unknown error", "Erreur inconnue"));
     } finally {
       setLoading(false);
     }
@@ -171,7 +195,7 @@ function App() {
   async function sendRawInput(event: FormEvent<HTMLFormElement>) {
     event.preventDefault();
     if (!selectedMachine || !rawInputName.trim()) {
-      addLog("Raw input blocked", "error", "Machine and input name are required.");
+      addLog(t("Raw input blocked", "Entree brute bloquee"), "error", t("Machine and input name are required.", "Machine et nom entree sont obligatoires."));
       return;
     }
     setLoading(true);
@@ -187,28 +211,40 @@ function App() {
       });
       addLog(`raw:${rawInputName}`, "ok", JSON.stringify(result, null, 2));
     } catch (error) {
-      addLog("Raw input", "error", error instanceof Error ? error.message : "Unknown error");
+      addLog(t("Raw input", "Entree brute"), "error", error instanceof Error ? error.message : t("Unknown error", "Erreur inconnue"));
     } finally {
       setLoading(false);
     }
   }
 
   const selectedMachineInfo = machines.find((machine) => machine.code === selectedMachine);
+  const machinePowerLabel = selectedMachineInfo?.powered_on ? t("Powered ON", "Sous tension") : t("Powered OFF", "Hors tension");
 
   return (
     <main className="shell">
       <section className="hero">
         <div>
-          <p className="eyebrow">Separate test console</p>
-          <h1>Passive Signal Simulator</h1>
+          <p className="eyebrow">{t("Separate test console", "Console de test separee")}</p>
+          <h1>{t("Passive Signal Simulator", "Simulateur signaux passifs")}</h1>
           <p className="hero__copy">
-            Simulate cycles, power states, stops, alarms, signal edges, debounce noise, and raw digital inputs without
-            adding test controls to the production dashboard.
+            {t(
+              "Simulate cycles, power states, stops, alarms, signal edges, debounce noise, and raw digital inputs without adding test controls to the production dashboard.",
+              "Simuler cycles, etats alimentation, arrets, alarmes, fronts signal, bruit anti-rebond et entrees digitales brutes sans ajouter de controles de test au tableau de production.",
+            )}
           </p>
         </div>
-        <div className="connection-card">
-          <span>Backend API</span>
-          <strong>{API_BASE_URL}</strong>
+        <div className="hero__side">
+          <label className="language-select">
+            <span>{t("Language", "Langue")}</span>
+            <select value={language} onChange={(event) => setLanguage(event.target.value as Language)}>
+              <option value="fr">Francais</option>
+              <option value="en">English</option>
+            </select>
+          </label>
+          <div className="connection-card">
+            <span>{t("Backend API", "API backend")}</span>
+            <strong>{API_BASE_URL}</strong>
+          </div>
         </div>
       </section>
 
@@ -216,16 +252,16 @@ function App() {
         <article className="panel panel--machine">
           <div className="panel__header">
             <div>
-              <p className="eyebrow">Target</p>
-              <h2>Machine</h2>
+              <p className="eyebrow">{t("Target", "Cible")}</p>
+              <h2>{t("Machine", "Machine")}</h2>
             </div>
             <button className="ghost-button" type="button" onClick={() => window.location.reload()}>
-              Reload
+              {t("Reload", "Recharger")}
             </button>
           </div>
 
           <label className="field">
-            <span>Machine code</span>
+            <span>{t("Machine code", "Code machine")}</span>
             <select value={selectedMachine} onChange={(event) => setSelectedMachine(event.target.value)}>
               {machines.map((machine) => (
                 <option key={machine.code} value={machine.code}>
@@ -240,16 +276,16 @@ function App() {
               <span className={`status-dot status-dot--${selectedMachineInfo.status}`} />
               <div>
                 <strong>{selectedMachineInfo.status}</strong>
-                <small>{selectedMachineInfo.powered_on ? "Powered ON" : "Powered OFF"}</small>
+                <small>{machinePowerLabel}</small>
               </div>
             </div>
           ) : (
-            <p className="empty">No machine returned by the backend.</p>
+            <p className="empty">{t("No machine returned by the backend.", "Aucune machine retournee par le backend.")}</p>
           )}
 
           <div className="numeric-grid">
             <label className="field">
-              <span>Cycle time sec</span>
+              <span>{t("Cycle time sec", "Temps cycle sec")}</span>
               <input
                 min="1"
                 step="0.1"
@@ -259,7 +295,7 @@ function App() {
               />
             </label>
             <label className="field">
-              <span>Burst count</span>
+              <span>{t("Burst count", "Nombre cycles")}</span>
               <input
                 min="1"
                 max="100"
@@ -274,10 +310,10 @@ function App() {
         <article className="panel panel--scenarios">
           <div className="panel__header">
             <div>
-              <p className="eyebrow">Cases</p>
-              <h2>Scenario Launcher</h2>
+              <p className="eyebrow">{t("Cases", "Cas")}</p>
+              <h2>{t("Scenario Launcher", "Lanceur scenarios")}</h2>
             </div>
-            {loading ? <span className="busy">Sending...</span> : null}
+            {loading ? <span className="busy">{t("Sending...", "Envoi...")}</span> : null}
           </div>
 
           <div className="scenario-grid">
@@ -289,8 +325,8 @@ function App() {
                 type="button"
                 onClick={() => runScenario(scenario.key)}
               >
-                <strong>{scenario.title}</strong>
-                <span>{scenario.description}</span>
+                <strong>{tt(scenario.title)}</strong>
+                <span>{tt(scenario.description)}</span>
               </button>
             ))}
           </div>
@@ -299,21 +335,21 @@ function App() {
         <article className="panel">
           <div className="panel__header">
             <div>
-              <p className="eyebrow">Manual</p>
-              <h2>Raw Passive Input</h2>
+              <p className="eyebrow">{t("Manual", "Manuel")}</p>
+              <h2>{t("Raw Passive Input", "Entree passive brute")}</h2>
             </div>
           </div>
           <form className="raw-form" onSubmit={sendRawInput}>
             <label className="field">
-              <span>Input name</span>
+              <span>{t("Input name", "Nom entree")}</span>
               <input value={rawInputName} onChange={(event) => setRawInputName(event.target.value)} />
             </label>
             <label className="field">
-              <span>Input value</span>
+              <span>{t("Input value", "Valeur entree")}</span>
               <input value={rawInputValue} onChange={(event) => setRawInputValue(event.target.value)} />
             </label>
             <button className="primary-button" disabled={loading || !selectedMachine} type="submit">
-              Send raw input
+              {t("Send raw input", "Envoyer entree brute")}
             </button>
           </form>
         </article>
@@ -321,15 +357,15 @@ function App() {
         <article className="panel panel--log">
           <div className="panel__header">
             <div>
-              <p className="eyebrow">Audit</p>
-              <h2>Simulation Log</h2>
+              <p className="eyebrow">{t("Audit", "Audit")}</p>
+              <h2>{t("Simulation Log", "Journal simulation")}</h2>
             </div>
             <button className="ghost-button" type="button" onClick={() => setLogs([])}>
-              Clear
+              {t("Clear", "Effacer")}
             </button>
           </div>
           <div className="log-list">
-            {logs.length === 0 ? <p className="empty">No simulator event sent yet.</p> : null}
+            {logs.length === 0 ? <p className="empty">{t("No simulator event sent yet.", "Aucun evenement simulateur envoye.")}</p> : null}
             {logs.map((log) => (
               <details className={`log-entry log-entry--${log.status}`} key={log.id} open={log.status === "error"}>
                 <summary>
diff --git a/simulator-ui/src/styles.css b/simulator-ui/src/styles.css
index 50d61ec..85c7ae7 100644
--- a/simulator-ui/src/styles.css
+++ b/simulator-ui/src/styles.css
@@ -96,6 +96,29 @@ h2 {
   backdrop-filter: blur(14px);
 }
 
+.hero__side {
+  display: grid;
+  gap: 12px;
+}
+
+.language-select {
+  display: grid;
+  gap: 6px;
+  border: 1px solid rgba(10, 47, 90, 0.1);
+  border-radius: 20px;
+  background: rgba(255, 255, 255, 0.86);
+  box-shadow: 0 12px 30px rgba(10, 47, 90, 0.08);
+  padding: 14px;
+}
+
+.language-select span {
+  color: var(--muted);
+  font-size: 0.76rem;
+  font-weight: 800;
+  letter-spacing: 0.12em;
+  text-transform: uppercase;
+}
+
 .connection-card {
   min-width: 300px;
   padding: 20px;
@@ -355,6 +378,10 @@ pre {
   .connection-card {
     min-width: 0;
   }
+
+  .hero__side {
+    width: 100%;
+  }
 }
 
 @media (max-width: 620px) {