I Built 66+ Free Browser Tools That Never Upload Your Files

Source: Dev.to

The Problem

Every time I needed to merge a PDF or compress an image, I had to upload my files to some random website. My tax documents, my photos, my work files — all going to servers I don’t control.

So I built BlitzTools — a platform with 66+ file‑processing tools that run 100 % in your browser. Your files never leave your device.

What It Does

PDF Tools

• Merge PDFs – Combine multiple PDFs into one
• Split PDF – Extract pages or split by range
• Compress PDF – Reduce file size
• DOC to PDF – Convert Word documents
• PDF Editor – Edit PDFs in the browser

Image Tools

• Compress Images – Up to 90 % smaller
• Resize Images – Any dimension
• Convert Formats – PNG, JPG, WebP, AVIF
• WebP to PNG – Format conversion

AI Tools

• Remove Objects – AI‑powered inpainting
• Remove Background – One‑click background removal
• Face Swap – In‑browser AI face swapping

Video Tools

• Compress Video – Reduce video size
• Convert Video – Format conversion
• Video to GIF – Create GIFs

The Tech Stack

Everything runs client‑side:

• Next.js with TypeScript for the frontend
• WebAssembly for near‑native processing speed
• Web Workers for non‑blocking background processing
• ONNX Runtime for AI model inference directly in the browser
• pdf-lib for PDF manipulation
• Canvas API for image processing

The AI tools (object removal, background removal, face swap) use ONNX models (RetinaFace, InsightFace) running entirely in the browser via WebAssembly—no API calls, no cloud processing.

Why Client‑Side?

Privacy isn’t just a feature; it’s the architecture. When your files never leave your device:

• No data breaches – There’s nothing to breach
• No upload wait – Processing starts instantly
• No file‑size limits – Your device’s memory is the only limit
• Works offline – Once loaded, no internet needed
• No account needed – Just open and use

Performance

WebAssembly gives near‑native speed. Compressing a 10 MB PDF takes ~2 seconds. Image format conversion is nearly instant. The AI tools take 3–5 seconds for inference depending on your hardware.

Web Workers keep the UI responsive during heavy processing—you can queue multiple files without the page freezing.

Try It

BlitzTools.app – Free, no account, no uploads. Just tools that work.

The project is open source: GitHub

I’d love to hear what tools you’d want added. Drop a comment or open an issue on GitHub!