Add Watermark to Image

The Watermark tool overlays text or a logo on any photo with full control over position, size, opacity, rotation, and tile-across-image mode. Text mode is great for handles, copyright lines, and 'DRAFT' or 'CONFIDENTIAL' stamps - configure font size, color, bold, italic, opacity, and rotation, then position with a 9-cell grid (top-left through bottom-right) or enable diagonal tiling. Logo mode accepts a separate PNG (transparent background recommended) and composites it at a configurable size and opacity.

Diagonal tiling repeats the watermark across the entire image at a 30-degree angle, creating a draft-style pattern that's much harder to crop out than a single corner watermark. Use it for confidential drafts shared for review, samples that shouldn't be reused without permission, or anything where the watermark needs to survive aggressive cropping. Single-position watermarks are friendlier visually; tiling is the harder-to-remove option.

Everything runs in your browser using the Canvas API. The original photo, optional logo file, and watermarked output all stay on your device. iPhone HEIC files are decoded locally with a WebAssembly module before the watermark step. No upload, no signup, no recurring watermark on the result.