Add a watermark to an image

FileGizmo adds a visible text watermark to JPG, PNG, and WebP images without uploading the source. Use it to label drafts, identify preview files, add a creator name, or mark internal assets before sharing. Choose an image, enter up to 80 characters, then select a relative text size, opacity, and position. The watermark can sit at the bottom left, bottom center, bottom right, or center of the image.

The worker scales text relative to the image dimensions so the result remains readable on both small graphics and larger photographs. A subtle dark backing improves contrast across mixed backgrounds while keeping the chosen text opacity visible. 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.