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Open sourceTools & open source2025

Shuiyin

Batch watermarks, fully local.

Batch-watermark ID cards and documents in the browser — nothing is ever uploaded.

Licence: GPL-3.0
Type: Open-source web tool
Formats: PNG · JPEG · GIF · WebP
Privacy: 100% local, no uploads

Overview

Shuiyin is a privacy-first watermark tool. Drop in a batch of images, set the text, colour, angle and spacing, preview instantly, then download them one by one or as a ZIP.

The problem

People watermark ID cards and business licences before sending copies, but most online tools upload those sensitive images to a server nobody can inspect.

How it works

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Everything runs on a canvas in the browser, so images never leave the device — it even works offline.
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A componentised React and TypeScript rebuild of joyqi’s open-source sfz project, with dedicated hooks for image management and watermark rendering.
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Released under GPL-3.0, so anyone can audit exactly how their files are handled.

What it does

Fully local

Processing happens in the browser; nothing is uploaded.

Real-time preview

See the watermark on every image as you adjust it.

Batch processing

Watermark many images in one go.

Flexible export

Download single images or everything as a ZIP.

Drag and drop

Drop PNG, JPEG, GIF or WebP files straight onto the page.

Custom watermark

Tune text, colour, opacity, angle, spacing and size.

Straight from the product.

Project details

Our role: Rebuilt, maintained and hosted as open source.
Platforms: Web · desktop & mobile browsers
Stack: React 18
TypeScript
Vite
Tailwind CSS
Canvas
JSZip
Licence: GPL-3.0
Source code: github.com/hloolx/shuiyin(opens in a new window)
Links: Live demo(opens in a new window)in.15o.cc
First release: 2025

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