Watermark Generator

Placing a watermark well is a judgement call that most people make badly. Drop it in the bottom-right corner by reflex and it lands on a face, disappears into a bright sky, or sits on the one part of the frame a cropper would cut off first. Doing it properly means looking at each photo and asking where the image is quiet enough to take a mark without fighting it.

This watermark maker does that analysis for you. Press Auto-place and it samples six candidate regions — the four corners plus the top and bottom centre — and measures two things in each: average brightness and how much that brightness varies. A low variance means a flat, uncluttered area: open sky, a plain wall, a blurred background. That is where a watermark reads cleanly and interferes least with the subject.

Brightness then decides the colour. The tool computes the WCAG relative luminance of the winning region and picks white type over a dark area or black type over a light one, keeping the contrast ratio at 4.5:1 or better — the same threshold used for readable body text. Opacity follows from the same numbers: a high-contrast, flat region needs less opacity to stay legible, so the mark is set lighter and intrudes less. A busy or low-contrast region gets more opacity and an outline instead.

What this is not is a neural network, and calling it one would be dishonest. It is image statistics — a luminance histogram and a standard deviation per region — which is exactly what the automatic watermark placement in every comparable tool amounts to. The advantage of doing it this way is that it runs in a few milliseconds on your own device, needs no model download, and produces the same result every time for the same photo.

Every automatic decision is a starting point, not a verdict. Position, colour, opacity and outline all stay editable, and you can drag the watermark anywhere on the preview afterwards. In batch mode you choose whether to run the analysis per photo — which is usually what you want, since a set of photos rarely has its quiet area in the same place twice — or to lock one position across the whole set for consistency.

Nearly every online watermark tool works the same way: you upload your photo, it is processed on a server you know nothing about, and a privacy policy is all that stands between your file and whatever happens next. For watermarking specifically, that is an odd bargain. The reason you are adding a watermark is usually that the image matters to you — a client shoot, a product photo, artwork you are about to post. Handing it to a stranger first is the opposite of protecting it.

ShotEdit inverts that. The moment you drop a file in, it is read from your disk straight into your browser tab. Canvas draws the watermark using your own CPU and GPU, and the finished image is handed back as a download. Nothing is transmitted, nothing is queued on a server, and nothing is stored — close the tab and every trace is gone from memory. You can confirm it yourself: open your browser's Network panel, watermark a photo, and watch that no request carries your image.

That architecture has practical consequences beyond privacy. There is no upload progress bar, because there is no upload — a 40 MP raw export is watermarked as fast as a screenshot. There is no file size cap imposed by an upload form, only what your device's memory can hold. There is no daily quota, because processing your photo costs ShotEdit nothing. And because the work happens locally, the page keeps working after you go offline.

EXIF metadata is stripped by default for the same reason. Photos from a phone routinely carry the GPS coordinates where they were taken, and a watermarked image is one you intend to publish. If you need the metadata preserved — photographers often do, for authorship fields — there is a switch for that when exporting JPG.

Add up to 100 photos in one go — by dragging a selection in, by picking multiple files, or by pasting from the clipboard. One set of watermark settings applies to the whole queue, the preview shows whichever image you have selected, and you can drop individual photos from the queue without starting over.

Because sizes are proportional, a batch of mixed dimensions comes out consistent: the watermark occupies the same fraction of every frame whether the photo is 800px or 8000px wide. This is the single most common failure of batch watermarking elsewhere, and it is the reason the size controls here are percentages.

Automatic placement can run per photo, so a set shot in different lighting gets a sensible position and colour for each frame rather than one position imposed on all of them. If you would rather have every image marked identically — usually the case for a product catalogue — turn that off and the position you set is applied across the set.

Processing is serial: one photo is drawn at full resolution, exported, and its canvas released before the next begins. That keeps memory flat instead of climbing with queue length, which is what lets a large batch of high-resolution photos run on a laptop or a phone without the tab being killed. When the queue finishes, download the images individually or take the whole set as a ZIP. Unlike most online tools, batch mode in this watermark generator is free and is not capped by a daily quota.

The question people ask most is what opacity a watermark should be. The honest answer is that it depends on what the watermark is for, and the two purposes pull in opposite directions. A mark meant to signal authorship on work you are happy to have shared should sit around 30–50% opacity: visible when looked for, ignorable when not. A mark meant to make an image unusable until someone licenses it belongs at 60–80% and across the middle of the frame, because a discreet corner mark is trivially cropped away. Choosing 50% for both is the common mistake — too heavy for a portfolio piece, too weak to protect a proof.

Size follows the same logic and should always be expressed proportionally. A text watermark at 4–6% of image width reads comfortably on a phone without dominating the composition; 8–12% is assertive; anything above 15% has stopped being a watermark and become a caption. Logos usually want 12–20% of image width, since a logo carries its meaning in its shape and needs more area than type to stay recognisable.

Position is where cropping enters the picture. Corners are the least intrusive and the easiest to remove — a 5% crop takes a corner mark with it. Anything you genuinely need to survive redistribution has to overlap the subject, or be tiled. That is the whole reason the tiled mode exists, and why proofing services have used tiled marks for decades despite how ugly they look.

Contrast decides legibility, and it is the reason automatic placement measures luminance rather than guessing. White text over a bright sky is invisible; black text over shadow is invisible. If your watermark must sit in a specific place regardless of what is underneath, turn on the outline: a contrasting stroke keeps type readable over any background, which is why broadcast subtitles have always used one.

On format: export to PNG when your watermark has soft edges or transparency and the file size does not matter, and to JPG when it does — the difference on a large photo is often several megabytes. WEBP sits between the two, keeping transparency at roughly PNG quality for a fraction of the size, and is supported by every current browser. If you are publishing to a platform that re-encodes uploads anyway, which is most social networks, exporting JPG at high quality loses nothing you would notice.