Your files never leave your device. Compress images, merge PDFs, convert video to GIF, and transcribe audio — no uploads, no accounts. A few server-powered tools are the exception, and each one is clearly labeled.
Most visited: ID Watermark ProtectorAdd anti-misuse watermarks to ID photos before sharing — free, in your browser.Popular tools
- Compress image to 100KB
- Merge PDF files online
- Convert video to GIF
- AI Excel formula generator *
- ID photo watermark protector
- Domain lookup
- Free audio to text transcriber
- Convert HEIC to JPG free
* The AI Excel formula generator is an exception to our on-device rule: it sends only your typed description to an AI service — never your files. Our Office-to-PDF converters (Word, Excel, PowerPoint, URL) also run on our secure servers: files are converted and never stored.
All tools
Media
Productivity
How it works
Every YuliusBox file tool runs on your device using modern browser technology — WebAssembly, the Canvas API, and on-device AI models like Whisper. When you drop a file into a tool, it is processed by your own CPU and GPU; nothing is sent to a server, stored in a database, or logged — and your files are never touched by ads or analytics. That means no queues, no file-size quotas imposed by server costs, and no privacy trade-offs — most tools even keep working offline once the page has loaded. The one exception is the AI Excel formula generator: it sends only your typed description to an AI service, and our Office-to-PDF converters (Word, Excel, PowerPoint, URL) run on our secure servers — files are converted, never stored. Verify the on-device tools yourself — open the DevTools Network tab and watch your files go nowhere. YuliusBox is open source (MIT) — view the code on GitHub.
No upload
Files are processed on your device and never sent to a server.
No signup
Every tool works instantly. No accounts, no email walls.
Free
All core tools are free to use, with no watermarks.
Made for sensitive files
Some files should never be uploaded anywhere. Client contracts before they are signed, resumes with home addresses, unreleased product screenshots, interview recordings — YuliusBox exists for exactly these. Because processing happens on your device, there is no server that could leak, subpoena, or train on your data. Freelancers can compress client assets without breaking NDAs, HR teams can merge resumes without a third party ever seeing them, and anyone on a metered or unreliable connection can keep working: once a tool page has loaded, most tools run fully offline.
This is also why there are no accounts. An account is a database of who processed what — we would rather not have it. If you ever doubt the claim, the proof is one click away: open your browser’s DevTools Network tab while using any on-device tool and watch your files go nowhere.