gdr-sys/image-optimizer-pro

Image Optimizer Pro is a single HTML file that compresses, renames, and watermarks large batches of images entirely inside your web browser. There is no server involved and no upload step: files never leave your device, and the tool keeps working even without an internet connection after the first load. The compression engine accepts PNG, JPEG, GIF, BMP, and TIFF files as input, and can output WebP, JPEG, PNG, or AVIF depending on what your browser supports. You control quality with a slider and can set a maximum resolution, or force exact fixed dimensions with padding for marketplace listings such as Amazon or Etsy. If the browser cannot actually produce the format you picked, the tool automatically falls back through WebP, then JPEG, then PNG, and flags any files affected so nothing is saved with the wrong extension. Processing runs in parallel using a pool of Web Workers sized to your computer's CPU cores, so the browser tab stays responsive even on large batches. On older browsers without this support, it falls back to single threaded processing with the same features. You can drag and drop individual files or whole folders, including nested subfolders, and the interface shows a folder structure panel with file counts. Beyond compression, the tool includes freeform or fixed ratio cropping, per image rotate and flip, and a batch rename feature with placeholders for original name, a progressive number, the date, or the source folder name, plus an SEO friendly option that lowercases names and replaces spaces with hyphens. A watermark feature supports either an uploaded logo image or custom text, with control over position, opacity, size, and rotation, shown in a live preview before processing. The project targets web developers preparing assets for deployment, e-commerce sellers formatting product photos, bloggers and content creators shrinking images for faster pages, photographers handling client deliverables in bulk, and anyone who prefers not to upload personal photos to a third-party server. It is released under the MIT license.