Protect image copyright and brand your visual assets with our free Online Watermark Tool. Overlay custom text captions or brand logo images onto photos. Features 9-point grid alignment presets, manual pixel offset controls, single or tiled matrix placement, rotation angles, opacity transparency, and stroke outlines. Processing runs 100% locally in your browser memory.
Drag and drop your main photo file or select one of the built-in template base images.
Choose Text or Logo mode, type your copyright caption or upload a logo, and adjust opacity, rotation, and position.
Click Download Watermarked Image to export your high-resolution signed image in PNG, JPEG, or WebP format.
Add copyright text with custom fonts and stroke outlines, or upload transparent PNG/SVG brand logos.
Position watermarks using 9 grid anchor presets, custom pixel offset sliders, or repeated matrix tiling.
Local HTML5 canvas overlay execution; photos and logo files are never sent to remote servers.
Digital image watermarking overlays text or graphic assets onto a base photo canvas using 2D context compositing. Global opacity transparency is controlled via ctx.globalAlpha, ensuring subtle watermark visibility without completely obscuring underlying image details.
Positioning transforms use coordinate matrix translation (ctx.translate(x, y)) and rotation (ctx.rotate(angle)). Single anchor mode calculates 9-point grid alignment coordinates (top-left, center, bottom-right, etc.) with custom margin offsets. Tiled mode loops through canvas X and Y axes with offset row shifts to construct a repeated diagonal watermark matrix.
Text watermarks support custom font families, bold/italic styles, and outer stroke outlines (ctx.strokeText) to guarantee high contrast legibility across both light and dark image backgrounds.