How it works
添加水印——ローカル。
每页叠加文字或画像——不アップロード。
🔒 100% Secure & Local: Your documents are processed entirely in your browser and never uploaded to any server.
ここにファイルをドラッグ＆ドロップ
Overlay text or a small image on every page. Up to 80 MB · 25 files / batch
添加水印——ローカル。
Conversions run in your tab with JavaScript — no desktop app required.
Files stay on your device during processing. We do not receive your uploads.
Heavy codecs and AI models run locally via Web Workers and WASM (FFmpeg.wasm, Transformers.js).
添加水印——ローカル。
扁平水印不可再编辑。 处理 100% 在ブラウザ内オフラインで行われます——ファイルから出ることはありません您的设备。
Yes. This tool is free convert online with no signup. Processing stays in your browser — no uploads.
You control quality settings. Choose higher quality for no quality loss when converting online.
Every conversion runs inside your browser tab using JavaScript and Web Workers. There is no background server queue and no account is required for core tools.
Your files are never uploaded to FreeConvertKit for processing. Originals, previews, and exports stay on your device unless you choose to download or share them yourself.
When codecs or AI models are needed, WebAssembly modules such as FFmpeg.wasm and Transformers.js execute locally — giving you desktop-class power with absolute file privacy.