diff --git a/ui/src/app/datasets/[datasetName]/page.tsx b/ui/src/app/datasets/[datasetName]/page.tsx
index 9deb7c7..ebcb47e 100644
--- a/ui/src/app/datasets/[datasetName]/page.tsx
+++ b/ui/src/app/datasets/[datasetName]/page.tsx
@@ -4,6 +4,7 @@ import { useEffect, useState, use, useMemo } from 'react';
 import { LuImageOff, LuLoader, LuBan } from 'react-icons/lu';
 import { FaChevronLeft } from 'react-icons/fa';
 import DatasetImageCard from '@/components/DatasetImageCard';
+import DatasetImageViewer from '@/components/DatasetImageViewer';
 import { Button } from '@headlessui/react';
 import AddImagesModal, { openImagesModal, useOpenImagesModalOnDrag } from '@/components/AddImagesModal';
 import { TopBar, MainContent } from '@/components/layout';
@@ -19,6 +20,8 @@ export default function DatasetPage({ params }: { params: { datasetName: string
   const datasetName = usableParams.datasetName;
   const [status, setStatus] = useState<'idle' | 'loading' | 'success' | 'error'>('idle');
   const { settings, isSettingsLoaded } = useSettings();
+  const [selectedImgPath, setSelectedImgPath] = useState<string | null>(null);
+  const [captionRefreshKeys, setCaptionRefreshKeys] = useState<Record<string, number>>({});
 
   const refreshImageList = (dbName: string) => {
     setStatus('loading');
@@ -137,12 +140,21 @@ export default function DatasetPage({ params }: { params: { datasetName: string
                 isAutoCaptioning={isAutoCaptioning}
                 imageUrl={img.img_path}
                 onDelete={() => refreshImageList(datasetName)}
+                onImageClick={() => setSelectedImgPath(img.img_path)}
+                captionRefreshKey={captionRefreshKeys[img.img_path] || 0}
               />
             ))}
           </div>
         )}
       </MainContent>
       <AddImagesModal />
+      <DatasetImageViewer
+        imgPath={selectedImgPath}
+        imageList={imgList.map(img => img.img_path)}
+        onChange={setSelectedImgPath}
+        refreshImages={() => refreshImageList(datasetName)}
+        onCaptionSaved={path => setCaptionRefreshKeys(prev => ({ ...prev, [path]: (prev[path] || 0) + 1 }))}
+      />
     </>
   );
 }
diff --git a/ui/src/components/DatasetImageCard.tsx b/ui/src/components/DatasetImageCard.tsx
index 8a4360a..8a8112c 100644
--- a/ui/src/components/DatasetImageCard.tsx
+++ b/ui/src/components/DatasetImageCard.tsx
@@ -13,6 +13,8 @@ interface DatasetImageCardProps {
   children?: ReactNode;
   className?: string;
   onDelete?: () => void;
+  onImageClick?: () => void;
+  captionRefreshKey?: number;
 }
 
 const DatasetImageCard: React.FC<DatasetImageCardProps> = ({
@@ -22,6 +24,8 @@ const DatasetImageCard: React.FC<DatasetImageCardProps> = ({
   children,
   className = '',
   onDelete = () => {},
+  onImageClick,
+  captionRefreshKey = 0,
 }) => {
   const cardRef = useRef<HTMLDivElement>(null);
   const [isVisible, setIsVisible] = useState<boolean>(false);
@@ -46,7 +50,7 @@ const DatasetImageCard: React.FC<DatasetImageCardProps> = ({
           data = `${data}`;
         }
         setCaption(data || '');
-        setSavedCaption(data || '');
+        setSavedCaption((data || '').trim());
         setIsCaptionLoaded(true);
       })
       .catch(error => {
@@ -92,6 +96,12 @@ const DatasetImageCard: React.FC<DatasetImageCardProps> = ({
     return () => clearInterval(interval);
   }, [isAutoCaptioning, inViewport, isVisible]);
 
+  // External trigger (e.g. caption edited in the full-screen viewer) — re-fetch
+  useEffect(() => {
+    if (captionRefreshKey === 0) return;
+    setIsCaptionLoaded(false);
+  }, [captionRefreshKey]);
+
   useEffect(() => {
     // Create intersection observer to check viewport visibility
     const observer = new IntersectionObserver(
@@ -194,9 +204,12 @@ const DatasetImageCard: React.FC<DatasetImageCardProps> = ({
                   src={`/api/img/${encodeURIComponent(imageUrl)}`}
                   alt={alt}
                   onLoad={handleLoad}
-                  className={`w-full h-full object-contain transition-opacity duration-300 ${
-                    loaded ? 'opacity-100' : 'opacity-0'
-                  }`}
+                  onClick={onImageClick}
+                  className={classNames('w-full h-full object-contain transition-opacity duration-300', {
+                    'opacity-100': loaded,
+                    'opacity-0': !loaded,
+                    'cursor-zoom-in': !!onImageClick,
+                  })}
                 />
               )}
             </>
@@ -250,7 +263,7 @@ const DatasetImageCard: React.FC<DatasetImageCardProps> = ({
             onBlur={saveCaption}
           >
             <textarea
-              className={classNames("w-full bg-transparent resize-none outline-none focus:ring-0 focus:outline-none", {
+              className={classNames('w-full bg-transparent resize-none outline-none focus:ring-0 focus:outline-none', {
                 'opacity-50 cursor-not-allowed': isAutoCaptioning,
               })}
               value={caption}
diff --git a/ui/src/components/DatasetImageViewer.tsx b/ui/src/components/DatasetImageViewer.tsx
new file mode 100644
index 0000000..669e87b
--- /dev/null
+++ b/ui/src/components/DatasetImageViewer.tsx
@@ -0,0 +1,399 @@
+'use client';
+import { useState, useEffect, useMemo, useCallback, useRef } from 'react';
+import { createPortal } from 'react-dom';
+import { Dialog, DialogBackdrop, DialogPanel } from '@headlessui/react';
+import { Cog } from 'lucide-react';
+import { Menu, MenuButton, MenuItem, MenuItems } from '@headlessui/react';
+import classNames from 'classnames';
+import { openConfirm } from './ConfirmModal';
+import { apiClient } from '@/utils/api';
+import { isVideo, isAudio } from '@/utils/basic';
+import AudioPlayer from './AudioPlayer';
+import { TransformWrapper, TransformComponent } from 'react-zoom-pan-pinch';
+
+interface Props {
+  imgPath: string | null; // current image path
+  imageList: string[]; // all dataset image paths
+  onChange: (nextPath: string | null) => void; // parent setter
+  refreshImages?: () => void;
+  onCaptionSaved?: (imgPath: string, caption: string) => void;
+}
+
+export default function DatasetImageViewer({ imgPath, imageList, onChange, refreshImages, onCaptionSaved }: Props) {
+  const [mounted, setMounted] = useState(false);
+  const [isOpen, setIsOpen] = useState(Boolean(imgPath));
+  const [caption, setCaption] = useState<string>('');
+  const [savedCaption, setSavedCaption] = useState<string>('');
+  const [isCaptionLoaded, setIsCaptionLoaded] = useState<boolean>(false);
+  const captionRef = useRef<string>('');
+  const savedCaptionRef = useRef<string>('');
+  const currentImgPathRef = useRef<string | null>(null);
+  const captionAbortRef = useRef<AbortController | null>(null);
+
+  useEffect(() => setMounted(true), []);
+
+  // open/close based on external value
+  useEffect(() => {
+    setIsOpen(Boolean(imgPath));
+  }, [imgPath]);
+
+  // after close, clear parent state post-transition
+  useEffect(() => {
+    if (!isOpen && imgPath) {
+      const t = setTimeout(() => onChange(null), 300);
+      return () => clearTimeout(t);
+    }
+  }, [isOpen, imgPath, onChange]);
+
+  // Keep refs in sync so we can save the latest caption on unmount/navigation
+  useEffect(() => {
+    captionRef.current = caption;
+  }, [caption]);
+  useEffect(() => {
+    savedCaptionRef.current = savedCaption;
+  }, [savedCaption]);
+
+  const filename = useMemo(() => {
+    if (!imgPath) return '';
+    if (imgPath.includes('\\')) {
+      const parts = imgPath.split('\\');
+      return parts[parts.length - 1];
+    }
+    return imgPath.split('/').pop() || '';
+  }, [imgPath]);
+
+  const currentIndex = useMemo(() => {
+    if (!imgPath) return -1;
+    return imageList.findIndex(img => img === imgPath);
+  }, [imgPath, imageList]);
+
+  const saveCaptionForPath = useCallback(
+    (path: string, value: string, prevSaved: string) => {
+      const trimmed = value.trim();
+      if (trimmed === prevSaved.trim()) return;
+      apiClient
+        .post('/api/img/caption', { imgPath: path, caption: trimmed })
+        .then(() => {
+          if (currentImgPathRef.current === path) {
+            setSavedCaption(trimmed);
+          }
+          onCaptionSaved?.(path, trimmed);
+        })
+        .catch(error => {
+          console.error('Error saving caption:', error);
+        });
+    },
+    [onCaptionSaved],
+  );
+
+  const saveCaption = useCallback(() => {
+    if (!imgPath) return;
+    saveCaptionForPath(imgPath, caption, savedCaption);
+  }, [imgPath, caption, savedCaption, saveCaptionForPath]);
+
+  // Fetch caption whenever the image changes; save any pending edits on the previous image first
+  useEffect(() => {
+    const previousPath = currentImgPathRef.current;
+    if (previousPath && previousPath !== imgPath) {
+      saveCaptionForPath(previousPath, captionRef.current, savedCaptionRef.current);
+    }
+    currentImgPathRef.current = imgPath;
+
+    if (!imgPath) {
+      setCaption('');
+      setSavedCaption('');
+      setIsCaptionLoaded(false);
+      return;
+    }
+
+    captionAbortRef.current?.abort();
+    const controller = new AbortController();
+    captionAbortRef.current = controller;
+    setIsCaptionLoaded(false);
+    setCaption('');
+    setSavedCaption('');
+
+    apiClient
+      .post('/api/caption/get', { imgPath }, { signal: controller.signal })
+      .then(res => res.data)
+      .then(data => {
+        if (controller.signal.aborted) return;
+        const text = data ? `${data}` : '';
+        setCaption(text);
+        setSavedCaption(text);
+        setIsCaptionLoaded(true);
+      })
+      .catch(error => {
+        if (controller.signal.aborted) return;
+        console.error('Error fetching caption:', error);
+        setIsCaptionLoaded(true);
+      });
+
+    return () => {
+      controller.abort();
+    };
+  }, [imgPath, saveCaptionForPath]);
+
+  // Save any pending caption when the viewer fully unmounts
+  useEffect(() => {
+    return () => {
+      const path = currentImgPathRef.current;
+      if (path) {
+        saveCaptionForPath(path, captionRef.current, savedCaptionRef.current);
+      }
+    };
+  }, [saveCaptionForPath]);
+
+  const onCancel = useCallback(() => {
+    saveCaption();
+    setIsOpen(false);
+  }, [saveCaption]);
+
+  const setImageAtIndex = useCallback(
+    (idx: number) => {
+      if (idx < 0 || idx >= imageList.length) return;
+      onChange(imageList[idx]);
+    },
+    [imageList, onChange],
+  );
+
+  const handlePrev = useCallback(() => {
+    if (currentIndex <= 0) return;
+    setImageAtIndex(currentIndex - 1);
+  }, [currentIndex, setImageAtIndex]);
+
+  const handleNext = useCallback(() => {
+    if (currentIndex === -1 || currentIndex >= imageList.length - 1) return;
+    setImageAtIndex(currentIndex + 1);
+  }, [currentIndex, imageList.length, setImageAtIndex]);
+
+  const handleDelete = useCallback(() => {
+    if (!imgPath) return;
+    openConfirm({
+      title: 'Delete Image',
+      message: `Are you sure you want to delete this image? This action cannot be undone.`,
+      type: 'warning',
+      confirmText: 'Delete',
+      onConfirm: () => {
+        apiClient
+          .post('/api/img/delete', { imgPath })
+          .then(() => {
+            console.log('Image deleted:', imgPath);
+            onChange(null);
+            if (refreshImages) refreshImages();
+          })
+          .catch(error => {
+            console.error('Error deleting image:', error);
+          });
+      },
+    });
+  }, [imgPath, onChange, refreshImages]);
+
+  // keyboard events while open — skip nav while caption textarea is focused
+  useEffect(() => {
+    const handleKeyDown = (event: KeyboardEvent) => {
+      if (!isOpen) return;
+      const target = event.target as HTMLElement | null;
+      const tag = target?.tagName;
+      const isTyping = tag === 'TEXTAREA' || tag === 'INPUT' || (target?.isContentEditable ?? false);
+
+      if (event.key === 'Escape') {
+        onCancel();
+        return;
+      }
+      if (isTyping) return;
+
+      switch (event.key) {
+        case 'ArrowLeft':
+        case 'ArrowUp':
+          handlePrev();
+          break;
+        case 'ArrowRight':
+        case 'ArrowDown':
+          handleNext();
+          break;
+        case 'Delete':
+        case 'Backspace':
+          handleDelete();
+          break;
+        default:
+          break;
+      }
+    };
+    window.addEventListener('keydown', handleKeyDown);
+    return () => window.removeEventListener('keydown', handleKeyDown);
+  }, [isOpen, onCancel, handlePrev, handleNext, handleDelete]);
+
+  // Touch swipe navigation
+  const touchStartRef = useRef<{ x: number; y: number } | null>(null);
+  const multiTouchRef = useRef(false);
+  const zoomedRef = useRef(false);
+  const SWIPE_THRESHOLD = 40;
+
+  const onTouchStart = useCallback((e: React.TouchEvent) => {
+    if (e.touches.length > 1) {
+      multiTouchRef.current = true;
+      touchStartRef.current = null;
+      return;
+    }
+    multiTouchRef.current = false;
+    const t = e.touches[0];
+    if (!t) return;
+    touchStartRef.current = { x: t.clientX, y: t.clientY };
+  }, []);
+
+  const onTouchEnd = useCallback(
+    (e: React.TouchEvent) => {
+      const start = touchStartRef.current;
+      touchStartRef.current = null;
+      if (multiTouchRef.current || zoomedRef.current) {
+        if (e.touches.length === 0) multiTouchRef.current = false;
+        return;
+      }
+      if (!start) return;
+      const t = e.changedTouches[0];
+      if (!t) return;
+      const dx = t.clientX - start.x;
+      const dy = t.clientY - start.y;
+      const absX = Math.abs(dx);
+      const absY = Math.abs(dy);
+      if (absX < SWIPE_THRESHOLD && absY < SWIPE_THRESHOLD) return;
+      if (absX > absY) {
+        if (dx < 0) handleNext();
+        else handlePrev();
+      } else {
+        if (dy < 0) handleNext();
+        else handlePrev();
+      }
+    },
+    [handleNext, handlePrev],
+  );
+
+  const handleCaptionKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault();
+      saveCaption();
+    }
+  };
+
+  const isCaptionCurrent = caption.trim() === savedCaption.trim();
+
+  if (!mounted) return null;
+
+  return createPortal(
+    <Dialog open={isOpen} onClose={onCancel} className="relative z-10">
+      <DialogBackdrop
+        transition
+        className="fixed inset-0 bg-gray-900/75 transition-opacity data-closed:opacity-0 data-enter:duration-300 data-enter:ease-out data-leave:duration-200 data-leave:ease-in"
+      />
+      <div className="fixed inset-0 z-10 w-screen overflow-y-auto">
+        <div className="flex min-h-full items-center justify-center p-0 sm:p-4 text-center">
+          <DialogPanel
+            transition
+            onTouchStart={onTouchStart}
+            onTouchEnd={onTouchEnd}
+            className="relative transform rounded-none sm:rounded-lg bg-gray-800 text-left shadow-xl transition-all data-closed:translate-y-4 data-closed:opacity-0 data-enter:duration-300 data-enter:ease-out data-leave:duration-200 data-leave:ease-in w-full sm:w-auto sm:max-w-[95%] sm:max-h-[95vh] data-closed:sm:translate-y-0 data-closed:sm:scale-95 flex flex-col overflow-hidden touch-pan-y"
+          >
+            <div className="overflow-hidden flex items-center justify-center">
+              {imgPath &&
+                (isAudio(imgPath) ? (
+                  <div className="w-[500px] h-[500px] max-w-full sm:max-w-[95vw] max-h-[70vh]">
+                    <AudioPlayer src={`/api/img/${encodeURIComponent(imgPath)}`} title={filename} autoPlay />
+                  </div>
+                ) : isVideo(imgPath) ? (
+                  <video
+                    src={`/api/img/${encodeURIComponent(imgPath)}`}
+                    className="w-auto h-auto max-w-full sm:max-w-[95vw] max-h-[70vh] object-contain"
+                    preload="none"
+                    playsInline
+                    loop
+                    autoPlay
+                    controls={true}
+                  />
+                ) : (
+                  <TransformWrapper
+                    key={imgPath}
+                    initialScale={1}
+                    minScale={1}
+                    maxScale={6}
+                    doubleClick={{ mode: 'toggle', step: 2 }}
+                    wheel={{ step: 0.2 }}
+                    panning={{ disabled: false, allowRightClickPan: false }}
+                    onTransform={(_ref, state) => {
+                      zoomedRef.current = state.scale > 1.01;
+                    }}
+                  >
+                    <TransformComponent>
+                      <img
+                        src={`/api/img/${encodeURIComponent(imgPath)}`}
+                        alt="Dataset Image"
+                        draggable={false}
+                        className="w-auto h-auto max-w-full sm:max-w-[95vw] max-h-[70vh] object-contain select-none !pointer-events-auto"
+                      />
+                    </TransformComponent>
+                  </TransformWrapper>
+                ))}
+            </div>
+            <div className="bg-gray-950 text-sm flex flex-col px-4 py-2 gap-2">
+              <div className="flex items-center justify-between gap-4">
+                <div className="text-xs text-gray-400 truncate min-w-0">
+                  <span className="text-gray-500 mr-1">File:</span>
+                  <span className="text-gray-300">{filename}</span>
+                </div>
+                <div className="text-xs text-gray-400 whitespace-nowrap">
+                  {currentIndex >= 0 ? `${currentIndex + 1} / ${imageList.length}` : ''}
+                </div>
+              </div>
+              <div
+                className={classNames('rounded border-2 bg-gray-900 transition-colors', {
+                  'border-blue-500': !isCaptionCurrent,
+                  'border-gray-700': isCaptionCurrent,
+                })}
+              >
+                <textarea
+                  className="w-full bg-transparent text-gray-100 text-sm p-2 resize-none outline-none focus:ring-0 focus:outline-none"
+                  placeholder={isCaptionLoaded ? 'Add a caption...' : 'Loading caption...'}
+                  value={caption}
+                  rows={3}
+                  onChange={e => setCaption(e.target.value)}
+                  onKeyDown={handleCaptionKeyDown}
+                  onBlur={saveCaption}
+                  disabled={!isCaptionLoaded}
+                />
+              </div>
+            </div>
+            <div className="absolute top-2 right-2 bg-gray-900 rounded-full p-1 leading-[0px] opacity-50 hover:opacity-100 z-20">
+              <Menu>
+                <MenuButton>
+                  <Cog />
+                </MenuButton>
+                <MenuItems
+                  anchor="bottom end"
+                  className="bg-gray-900 border border-gray-700 rounded shadow-lg w-48 px-2 py-2 mt-1 z-50"
+                >
+                  {imgPath && isAudio(imgPath) && (
+                    <MenuItem>
+                      <a
+                        className="cursor-pointer px-4 py-1 hover:bg-gray-800 rounded block"
+                        href={`/api/img/${encodeURIComponent(imgPath)}`}
+                        download={filename}
+                      >
+                        Download
+                      </a>
+                    </MenuItem>
+                  )}
+                  <MenuItem>
+                    <div className="cursor-pointer px-4 py-1 hover:bg-gray-800 rounded" onClick={handleDelete}>
+                      Delete Image
+                    </div>
+                  </MenuItem>
+                </MenuItems>
+              </Menu>
+            </div>
+          </DialogPanel>
+        </div>
+      </div>
+    </Dialog>,
+    document.body,
+  );
+}