This 2 That

Why You Shouldn't Upload Sensitive Files to Online Converters

Published March 11, 2026 | 7 min read

You need to convert a PDF. You Google "PDF converter," click the first result, and upload your file. Easy, right?

But wait. That PDF contains your tax returns. Or a client's contract. Or medical records. And you just handed it to a random website.

This article explains why uploading files to online converters is risky, and what to do instead.

The Privacy Nightmare of Upload-Based Converters

Most "free" online file converters work like this:

  1. You upload your file to their server
  2. Their server processes it (PDF → JPG, compress, etc.)
  3. You download the converted file
  4. They claim to delete it after "a few hours"

But here's what they don't tell you:

1. Your File is Stored (Even Temporarily)

The second you upload, your file lives on someone else's server. Even if they delete it "after processing," that could be minutes or hours where it's accessible.

Questions to ask:

Most free converters don't answer these questions in their privacy policy.

2. Data Breaches Happen

Real examples:

Even well-meaning companies make mistakes. Your file could end up in a data breach through no fault of your own.

3. Terms of Service Are Scary

Buried in the fine print, many converters include clauses like:

"By uploading content, you grant us a worldwide, non-exclusive, royalty-free license to use, reproduce, and modify your files..."

Translation: They can keep and use your files however they want.

Some services explicitly reserve the right to:

4. Metadata Leaks

Even if they don't read your file, metadata reveals a lot:

This data is often sold to advertisers or data brokers.

What Types of Files Should Never Be Uploaded?

🔴 High Risk (Never Upload)

🟡 Medium Risk (Be Cautious)

🟢 Low Risk (Probably Safe)

Rule of thumb: If you wouldn't email it to a stranger, don't upload it to a free converter.

The Solution: Client-Side Conversion

Client-side conversion means the conversion happens in your browser, not on a server.

How It Works:

  1. You visit a converter website (e.g., this-2-that.com)
  2. You select a file on your computer
  3. JavaScript in your browser processes the file
  4. The converted file is created locally
  5. You download it (from your own browser memory)

Your file NEVER leaves your device. Zero upload.

Benefits of Client-Side Tools:

Limitations:

For 95% of conversions, client-side is superior.

Real-World Scenarios

Scenario 1: Lawyer Converting Client Files

Risk: Confidential attorney-client materials leaked via converter.

Consequence: Malpractice lawsuit, bar complaints, loss of client trust.

Solution: Use client-side converter like This 2 That.

Scenario 2: HR Manager Compressing Resumes

Risk: Applicant SSNs, addresses exposed in data breach.

Consequence: GDPR violation (up to €20M fine), identity theft lawsuits.

Solution: Process locally with no upload.

Scenario 3: Freelancer Converting Client Invoice

Risk: Invoice data sold to competitors.

Consequence: Competitors undercut pricing, loss of business.

Solution: Client-side conversion keeps trade secrets private.

How to Tell If a Converter is Client-Side

Look for these signs:

✅ Client-Side (Safe):

❌ Upload-Based (Risky):

When in doubt, check the Network tab in your browser's DevTools (F12). If you see POST requests to external servers, it's uploading.

Best Practices for File Security

  1. Use client-side tools for sensitive files (This 2 That, etc.)
  2. Never upload files with PII (names, SSN, addresses)
  3. Check privacy policies before using any online service
  4. Use desktop software for highly confidential work (Adobe Acrobat, GIMP, etc.)
  5. Encrypt before uploading if you must use a cloud service
  6. Delete uploaded files as soon as possible (if the service allows)
  7. Use VPN to hide IP address when uploading

Conclusion

Uploading files to free online converters is convenient. But convenience isn't worth the privacy risk.

For sensitive documents:

Your files, your privacy, your security. Don't hand them to strangers.

Try Client-Side Conversion (100% Private) →

Last updated: March 11, 2026