Sellers who photograph their own stock often see those photos reused by other sellers. A watermark does not stop that, but it makes copying less attractive and keeps your shop name on the photo wherever it travels. Adding one by hand to fifty photos is the part nobody wants to do.
Here you set the stamp once on a live preview, and every photo in the batch receives the same look, sized to fit its own pixels. Photos stay in your browser and are never uploaded.
Check the rules before you stamp
Many marketplaces ask sellers to keep watermarks and logos off the main product image, and a stamped photo could be held back from a listing. Rules differ by marketplace and category, so read your own seller center policy. Gallery photos and social media posts are often a safer place for a watermark.
Keep your unstamped originals, because a watermark cannot be cleanly removed later. Stamped copies download as new files, and your originals are not changed.
Which position works best
A corner stamp keeps the product clean but is easy to crop away. A repeating pattern is much harder to remove, though it distracts from the product. A common middle ground is a centred stamp at low opacity, so the product is still clear and the mark is still difficult to cut out.