diff --git a/public/admin.css b/public/admin.css
index 8f8cc33..8d86e9b 100644
--- a/public/admin.css
+++ b/public/admin.css
@@ -706,6 +706,20 @@ label { display: grid; gap: 6px; color: var(--muted); font-size: 13px; }
 .message .by { font-size: 12px; color: var(--muted); margin-bottom: 4px; }
 .message p { margin: 0; white-space: pre-wrap; }
 .message a { color: var(--brand); display: inline-block; margin-top: 6px; }
+.translation {
+  margin-top: 7px;
+  padding: 8px 9px;
+  border-left: 3px solid var(--brand);
+  border-radius: 6px;
+  background: #f4faf7;
+}
+.translation span {
+  display: block;
+  margin-bottom: 4px;
+  color: var(--muted);
+  font-size: 11px;
+  font-weight: 700;
+}
 .read-receipt {
   align-self: flex-end;
   margin-top: -4px;
diff --git a/public/admin.html b/public/admin.html
index e11b349..4f4ad30 100644
--- a/public/admin.html
+++ b/public/admin.html
@@ -165,6 +165,20 @@
               </label>
               <label class="setting-switch">Opakovat do otevreni chatu <input id="adminSoundRepeat" type="checkbox"></label>
               <button id="adminSoundTest" type="button">Otestovat zvuk</button>
+              <fieldset class="effect-settings">
+                <legend>AI preklady</legend>
+                <label><input id="translationEnabled" type="checkbox"> zapnout preklady</label>
+                <label>Jazyk operatora
+                  <select id="operatorLanguage">
+                    <option value="cs">Cestina</option>
+                    <option value="sk">Slovenstina</option>
+                    <option value="pl">Polstina</option>
+                    <option value="en">Anglictina</option>
+                    <option value="de">Nemcina</option>
+                  </select>
+                </label>
+                <label>OpenAI model <input id="translationModel" placeholder="gpt-5.6-luna"></label>
+              </fieldset>
             </div>
           </section>
         </aside>
diff --git a/public/admin.js b/public/admin.js
index 420b1d5..de5e321 100644
--- a/public/admin.js
+++ b/public/admin.js
@@ -79,6 +79,9 @@ $("#adminSoundRepeat").addEventListener("change", (event) => {
 $("#adminSoundTest").addEventListener("click", () => {
   playNotifySound({ ignoreMuted: true });
 });
+$("#translationEnabled").addEventListener("change", saveTranslationSettings);
+$("#operatorLanguage").addEventListener("change", saveTranslationSettings);
+$("#translationModel").addEventListener("change", saveTranslationSettings);
 document.querySelectorAll("[data-settings-tab]").forEach((button) => {
   button.addEventListener("click", () => {
     const tab = button.dataset.settingsTab;
@@ -385,6 +388,21 @@ function renderSite() {
   form.messageBadge.checked = s.notifications?.badgeOnAdminReply !== false;
   form.messageLabel.checked = s.notifications?.labelOnAdminReply !== false;
   form.messageWiggle.checked = s.notifications?.wiggleOnAdminReply !== false;
+  $("#translationEnabled").checked = Boolean(s.translations?.enabled);
+  $("#operatorLanguage").value = s.translations?.operatorLanguage || "cs";
+  $("#translationModel").value = s.translations?.model || "gpt-5.6-luna";
+}
+
+async function saveTranslationSettings() {
+  if (!state.site) return;
+  const settings = structuredClone(state.site.settings);
+  settings.translations = {
+    ...(settings.translations || {}),
+    enabled: $("#translationEnabled").checked,
+    operatorLanguage: $("#operatorLanguage").value,
+    model: $("#translationModel").value.trim() || "gpt-5.6-luna"
+  };
+  await saveSite({ settings, isOnline: state.site.isOnline });
 }
 
 function renderConversations() {
@@ -511,13 +529,28 @@ function renderActive() {
   $("#messages").innerHTML = messages.map((message) => `
     <article class="message ${message.senderType}">
       <div class="by">${escapeHtml(message.senderName || message.senderType)} · ${escapeHtml(message.createdAt)}</div>
-      ${message.body ? `<p>${escapeHtml(message.body)}</p>` : ""}
+      ${renderMessageBody(message)}
       ${renderAttachments(message.attachments)}
     </article>
   `).join("") + adminReadReceipt(conversation, messages);
   $("#messages").scrollTop = $("#messages").scrollHeight;
 }
 
+function renderMessageBody(message) {
+  const original = message.body ? `<p>${escapeHtml(message.body)}</p>` : "";
+  if (!message.translatedBody) return original;
+  const label = message.senderType === "visitor"
+    ? `Preklad do ${escapeHtml(message.translatedLanguage || "")}`
+    : `Odeslano zakaznikovi ${escapeHtml(message.translatedLanguage || "")}`;
+  return `
+    ${original}
+    <div class="translation">
+      <span>${label}</span>
+      <p>${escapeHtml(message.translatedBody)}</p>
+    </div>
+  `;
+}
+
 async function renameVisitor(visitorToken) {
   if (!state.active?.conversation || !visitorToken) return;
   const currentName = conversationVisitorName(state.active.conversation);
diff --git a/public/widget.js b/public/widget.js
index 900da89..dfc8797 100644
--- a/public/widget.js
+++ b/public/widget.js
@@ -356,7 +356,8 @@
     messages.innerHTML = "";
     let lastAdminName = null;
     for (const message of data.messages) {
-      addMessage(messages, message.senderType, message.senderName, message.body, message.attachments || [], lastAdminName);
+      const body = message.senderType === "admin" ? (message.translatedBody || message.body) : message.body;
+      addMessage(messages, message.senderType, message.senderName, body, message.attachments || [], lastAdminName);
       if (message.senderType === "admin") lastAdminName = message.senderName || "Operator";
       else lastAdminName = null;
     }
diff --git a/server.js b/server.js
index 209d03f..bce0de6 100644
--- a/server.js
+++ b/server.js
@@ -16,6 +16,8 @@ const PORT = Number(process.env.PORT || 3400);
 const PUBLIC_BASE_URL = (process.env.PUBLIC_BASE_URL || `http://localhost:${PORT}`).replace(/\/$/, "");
 const AUTH_SECRET = process.env.AUTH_SECRET || "dev-secret-change-me";
 const COOKIE_NAME = "mf_session";
+const OPENAI_API_KEY = process.env.OPENAI_API_KEY || "";
+const OPENAI_TRANSLATION_MODEL = process.env.OPENAI_TRANSLATION_MODEL || "gpt-5.6-luna";
 const ALLOWED_IMAGE_TYPES = new Set(["image/jpeg", "image/png", "image/webp", "image/gif", "image/avif"]);
 const ALLOWED_IMAGE_EXTENSIONS = new Set([".jpg", ".jpeg", ".png", ".webp", ".gif", ".avif"]);
 const MAX_ATTACHMENT_BYTES = 3_000_000;
@@ -141,6 +143,7 @@ function initDb() {
       timezone TEXT,
       ip TEXT,
       country_code TEXT,
+      customer_language TEXT,
       vpn_risk INTEGER NOT NULL DEFAULT 0,
       visitor_seen_at TEXT,
       last_message_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
@@ -154,6 +157,10 @@ function initDb() {
       sender_type TEXT NOT NULL,
       sender_name TEXT,
       client_message_id TEXT,
+      original_language TEXT,
+      translated_body TEXT,
+      translated_language TEXT,
+      translation_status TEXT,
       body TEXT NOT NULL,
       created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
     );
@@ -212,7 +219,12 @@ function initDb() {
     db.prepare("UPDATE visitor_sessions SET last_activity_at = last_seen_at WHERE last_activity_at IS NULL").run();
   }
   ensureColumn("conversations", "visitor_seen_at", "TEXT");
+  ensureColumn("conversations", "customer_language", "TEXT");
   ensureColumn("messages", "client_message_id", "TEXT");
+  ensureColumn("messages", "original_language", "TEXT");
+  ensureColumn("messages", "translated_body", "TEXT");
+  ensureColumn("messages", "translated_language", "TEXT");
+  ensureColumn("messages", "translation_status", "TEXT");
   db.exec("CREATE UNIQUE INDEX IF NOT EXISTS idx_messages_client_id ON messages(conversation_id, client_message_id) WHERE client_message_id IS NOT NULL");
 }
 
@@ -280,6 +292,11 @@ function defaultSettings() {
       badgeOnAdminReply: true,
       labelOnAdminReply: true,
       wiggleOnAdminReply: true
+    },
+    translations: {
+      enabled: false,
+      operatorLanguage: "cs",
+      model: OPENAI_TRANSLATION_MODEL
     }
   };
 }
@@ -560,9 +577,10 @@ async function createConversation(req, res) {
 
     const messageId = insertMessage(conversationId, "visitor", info.name || "Visitor", String(body.message || "").trim(), clientMessageId);
     saveAttachments(conversationId, messageId, body.attachments || []);
-    return conversationId;
+    return { conversationId, messageId };
   });
   const insert = insertConversation();
+  await translateStoredMessage(insert.conversationId, insert.messageId, "visitor", body);
 
   const conversation = findConversation(publicId);
   publish("admin", { type: "conversation:new", conversation: formatConversationSummary(conversation) });
@@ -584,6 +602,7 @@ async function createVisitorMessage(req, res, url) {
   const messageId = insertMessage(conversation.id, "visitor", conversation.visitor_name || "Visitor", String(body.message || "").trim(), clientMessageId);
   saveAttachments(conversation.id, messageId, body.attachments || []);
   updateVisitorContext(conversation.id, body);
+  await translateStoredMessage(conversation.id, messageId, "visitor", body);
   markConversationUnread(conversation.id);
   bumpConversation(conversation.id, conversation.status === "resolved" ? "open" : conversation.status);
   const updated = findConversation(conversation.public_id);
@@ -610,6 +629,7 @@ async function createAdminMessage(req, res, url) {
   if (!conversation) return json(res, 404, { error: "conversation_not_found" });
   const messageId = insertMessage(conversation.id, "admin", req.adminUser.displayName || req.adminUser.username, String(body.message || "").trim());
   saveAttachments(conversation.id, messageId, body.attachments || []);
+  await translateStoredMessage(conversation.id, messageId, "admin", body);
   bumpConversation(conversation.id, conversation.status === "new" ? "open" : conversation.status);
   markConversationSeen(conversation.id);
   const updated = findConversation(conversation.public_id);
@@ -680,9 +700,9 @@ function publish(key, event) {
 
 function insertMessage(conversationId, senderType, senderName, body, clientMessageId = null) {
   return db.prepare(`
-    INSERT INTO messages (conversation_id, sender_type, sender_name, client_message_id, body)
-    VALUES (?, ?, ?, ?, ?)
-  `).run(conversationId, senderType, senderName, clientMessageId, body).lastInsertRowid;
+    INSERT INTO messages (conversation_id, sender_type, sender_name, client_message_id, body, translation_status)
+    VALUES (?, ?, ?, ?, ?, ?)
+  `).run(conversationId, senderType, senderName, clientMessageId, body, body ? "pending" : "skipped").lastInsertRowid;
 }
 
 function messageExists(conversationId, clientMessageId) {
@@ -707,6 +727,124 @@ function normalizeClientMessageId(value) {
   return /^[a-zA-Z0-9_-]{8,80}$/.test(text) ? text : null;
 }
 
+async function translateStoredMessage(conversationId, messageId, senderType, body) {
+  const message = db.prepare("SELECT * FROM messages WHERE id = ? AND conversation_id = ?").get(messageId, conversationId);
+  if (!message || !message.body.trim()) return markMessageTranslation(messageId, null, null, null, "skipped");
+
+  const conversation = findConversationById(conversationId);
+  const settings = getTranslationSettings();
+  if (!settings.enabled) return markMessageTranslation(messageId, null, null, null, "disabled");
+  if (!OPENAI_API_KEY) return markMessageTranslation(messageId, null, null, null, "missing_key");
+
+  const targetLanguage = senderType === "visitor"
+    ? settings.operatorLanguage
+    : normalizeLanguage(conversation.customer_language || conversation.language || body.language || settings.operatorLanguage);
+  if (!targetLanguage) return markMessageTranslation(messageId, null, null, null, "skipped");
+
+  try {
+    const result = await translateText(message.body, targetLanguage, settings.model);
+    const sourceLanguage = normalizeLanguage(result.sourceLanguage);
+    const translatedText = String(result.translatedText || "").trim();
+    const translatedLanguage = normalizeLanguage(result.translatedLanguage || targetLanguage);
+    const sameLanguage = sourceLanguage && translatedLanguage && sourceLanguage === translatedLanguage;
+
+    if (senderType === "visitor" && sourceLanguage) {
+      db.prepare("UPDATE conversations SET customer_language = COALESCE(?, customer_language), updated_at = CURRENT_TIMESTAMP WHERE id = ?").run(sourceLanguage, conversationId);
+    }
+
+    if (!translatedText || sameLanguage) {
+      return markMessageTranslation(messageId, sourceLanguage, null, translatedLanguage, sameLanguage ? "same_language" : "empty");
+    }
+    markMessageTranslation(messageId, sourceLanguage, translatedText, translatedLanguage, "translated");
+  } catch (error) {
+    console.error("translation_failed", error.message);
+    markMessageTranslation(messageId, null, null, targetLanguage, "failed");
+  }
+}
+
+function markMessageTranslation(messageId, sourceLanguage, translatedBody, translatedLanguage, status) {
+  db.prepare(`
+    UPDATE messages
+    SET original_language = ?,
+        translated_body = ?,
+        translated_language = ?,
+        translation_status = ?
+    WHERE id = ?
+  `).run(sourceLanguage, translatedBody, translatedLanguage, status, messageId);
+}
+
+async function translateText(text, targetLanguage, model) {
+  const response = await fetch("https://api.openai.com/v1/responses", {
+    method: "POST",
+    headers: {
+      "Authorization": `Bearer ${OPENAI_API_KEY}`,
+      "Content-Type": "application/json"
+    },
+    body: JSON.stringify({
+      model,
+      input: [
+        {
+          role: "system",
+          content: "You translate live chat messages for an e-commerce support team. Return only compact JSON with keys sourceLanguage, translatedLanguage, translatedText. Preserve meaning, product terms, numbers, names, URLs, and tone. Do not answer the customer."
+        },
+        {
+          role: "user",
+          content: JSON.stringify({
+            targetLanguage,
+            text
+          })
+        }
+      ]
+    })
+  });
+  if (!response.ok) throw new Error(`OpenAI HTTP ${response.status}`);
+  const data = await response.json();
+  return parseTranslationJson(outputTextFromResponse(data));
+}
+
+function parseTranslationJson(value) {
+  try {
+    const text = String(value || "").trim().replace(/^```(?:json)?/i, "").replace(/```$/, "").trim();
+    const parsed = JSON.parse(text);
+    return {
+      sourceLanguage: parsed.sourceLanguage,
+      translatedLanguage: parsed.translatedLanguage,
+      translatedText: parsed.translatedText
+    };
+  } catch {
+    throw new Error("OpenAI translation response was not valid JSON");
+  }
+}
+
+function outputTextFromResponse(data) {
+  if (data.output_text) return data.output_text;
+  const chunks = [];
+  for (const item of data.output || []) {
+    for (const content of item.content || []) {
+      if (content.type === "output_text" && content.text) chunks.push(content.text);
+      if (content.type === "text" && content.text) chunks.push(content.text);
+    }
+  }
+  return chunks.join("");
+}
+
+function getTranslationSettings() {
+  const site = getDefaultSite();
+  const settings = parseJson(site.settings_json, defaultSettings());
+  const translations = { ...defaultSettings().translations, ...(settings.translations || {}) };
+  return {
+    enabled: Boolean(translations.enabled),
+    operatorLanguage: normalizeLanguage(translations.operatorLanguage) || "cs",
+    model: String(translations.model || OPENAI_TRANSLATION_MODEL).trim() || OPENAI_TRANSLATION_MODEL
+  };
+}
+
+function normalizeLanguage(value) {
+  const text = String(value || "").trim().toLowerCase().replace("_", "-");
+  if (!text) return "";
+  return text.split("-")[0].slice(0, 8);
+}
+
 function saveAttachments(conversationId, messageId, attachments) {
   for (const attachment of attachments.slice(0, 3)) {
     if (!attachment.dataBase64 || !attachment.name) continue;
@@ -827,6 +965,10 @@ function conversationDetails(conversation) {
       senderType: message.sender_type,
       senderName: message.sender_name,
       body: message.body,
+      originalLanguage: message.original_language,
+      translatedBody: message.translated_body,
+      translatedLanguage: message.translated_language,
+      translationStatus: message.translation_status,
       createdAt: message.created_at,
       attachments: attachments
         .filter((item) => item.message_id === message.id)
@@ -842,6 +984,7 @@ function formatConversationSummary(row) {
     siteKey: row.site_key,
     status: row.status,
     visitorToken: row.visitor_token,
+    customerLanguage: row.customer_language || "",
     visitorInitials: visitorInitials(row.visitor_token),
     visitorLabel: row.visitor_display_name || visitorLabel(row.visitor_token),
     visitorDefaultLabel: visitorLabel(row.visitor_token),
@@ -892,6 +1035,7 @@ function formatSite(site) {
   const settings = parseJson(site.settings_json, defaultSettings());
   settings.notifications = { ...defaultSettings().notifications, ...(settings.notifications || {}) };
   settings.launcherEffects = { ...defaultSettings().launcherEffects, ...(settings.launcherEffects || {}) };
+  settings.translations = { ...defaultSettings().translations, ...(settings.translations || {}) };
   return {
     id: site.id,
     siteKey: site.site_key,
@@ -954,6 +1098,11 @@ function findConversation(publicId) {
   `).get(publicId);
 }
 
+function findConversationById(id) {
+  const row = db.prepare("SELECT public_id FROM conversations WHERE id = ?").get(id);
+  return row ? findConversation(row.public_id) : null;
+}
+
 function markConversationSeen(conversationId) {
   db.prepare("UPDATE conversations SET admin_seen_at = CURRENT_TIMESTAMP WHERE id = ?").run(conversationId);
 }