You're about to share a design, a screenshot, or a preview, and you don't want it floating around with no indication of where it came from. A watermark does two jobs: it marks ownership and it signals "this is a draft," which quietly discourages uncredited reuse.
The Image Watermark tool stamps text onto your image right in the browser. Set the text, pick a position from a nine-point grid, dial in opacity, and choose a color. A moderate opacity keeps the image usable while the mark stays visible — crank it to full only when you want the text to dominate. The image never leaves your device.
Why local? Because the thing you're protecting is the image itself. Uploading it to a watermarking service to get a marked copy back is the exact exposure you're trying to avoid. In-browser stamping means the only copy that ever existed of the marked version is the one on your machine.
After stamping, you may want a different container format. The Image Converter tool flips between PNG, JPEG, and WebP so the watermarked file lands in whatever format your CMS or client expects.
Quick path: open Image Watermark, type your mark, set position and opacity, download the PNG, then convert if the destination needs JPEG or WebP.