I Tested 10 Online File Converters — None of Them Were Actually Private

Last month a client sent me a PDF with sensitive financial data and asked me to convert it to a spreadsheet. I Googled “free PDF to CSV converter” and picked the first result.

Then I read their privacy policy. Section 4.3 granted them a license to “store, process, and analyze” uploaded content for “service improvement.” That’s corporate-speak for “we read your files.”

What I Found

I tested 10 popular online converters by monitoring network requests during file uploads. Every single one sent the file to a remote server. Only one disclosed this clearly in the UI — the rest buried it in 15-page privacy policies.

The Alternative

I built formlyapp.org as a universal converter that runs entirely in the browser. PDF to JPG, JSON to CSV, XML to JSON, HEIC to PNG — all processed locally via Canvas API, FileReader, and browser-native parsers.

Also built dedicated converters for specific formats:

• svg2png.org for vector graphics
• webp2png.io for next-gen image formats

How to Verify

Open any of these tools in Chrome. Open DevTools → Network tab. Process a file. You’ll see zero upload requests. Every byte stays in browser memory.

The technology has existed for years — Canvas, Blob APIs, Web Workers. The only reason most converters upload your files is that it was easier to build that way. It’s not easier anymore.