Add a watermark to an image

FileGizmo adds a visible text or logo watermark to JPG, PNG, and WebP images without uploading the source or the logo. Use it to label drafts, identify preview files, add a creator name or a shop logo, or mark internal assets before sharing. Choose an image, enter up to 80 characters or pick your logo, then select a size, opacity, and style: placed freely, one diagonal mark, or tiled across the picture. Save those settings as a named template on this device to reuse them with another batch. A logo template remembers the settings but not the logo file, so you choose that file again. The logo keeps its own shape and transparency, and each copy can be dragged, resized and turned on the preview.

Up to twenty images can be handed over at once and the same setting applied to each. They run one at a time, and each gets its own row and its own download, with one button for all of them as a ZIP. A file that cannot be read loses only itself; the ones after it still finish.

The worker scales text relative to the image dimensions so the result remains readable on both small graphics and larger photographs. A dark outline around the white text keeps it readable on bright and dark areas alike, at the chosen opacity. Watermarks are a deterrent, not cryptographic protection: another person may crop or edit them, so do not treat the result as access control. Image decoding and drawing happen in a dedicated browser worker, and temporary preview URLs are removed when the workflow resets. PNG transparency is supported, while JPEG and WebP use high-quality output encoding. Inspect the preview for overlap with important details before downloading and distributing the marked image.