What does it diagnose?

Digital signature PKCS#7 padding errors, missing/broken font embedding, xref table corruption, PDF/A violations, metadata encoding issues, Producer/Creator info, and more.

Is my PDF sent to Nadoo's servers?

No. 100% in-browser analysis. Open your network tab and verify — no PDF data leaves your device.

Can it tell me which library produced the PDF?

Yes — extracted from the PDF's Producer/Creator metadata. Useful for tracing compatibility issues to a specific tool.

What about large PDFs?

Recommended under 100MB. Very large PDFs may be slow on mobile.

How do I avoid broken PDFs in the first place?

Use Nadoo e-contract — its in-house signing engine produces only valid PDFs and auto-validates every step.

PDF Diagnose

Free PDF Diagnosis

Name: Free PDF Diagnosis — Find Out Why Your PDF Is Broken
Availability: InStock
Author: Nadoo

Drag & drop a PDF and we'll analyze it in your browser. Digital signature errors, font issues, structural corruption — find out exactly what's wrong. Files never uploaded.

All processing happens in your browser. Your files are never uploaded anywhere.

Diagnose a PDF in 3 steps

Drag & drop PDF

Drop your PDF or click to select. Files are processed only in your browser.

Auto diagnosis report

Digital signature padding, font embedding, xref, metadata — all checked as a checklist.

View root-cause guide

Click any issue for the typical cause and a remediation direction.

100% browser analysis

Your PDF is never
uploaded anywhere

Sensitive contracts, HR docs, financial files — safe. All analysis happens in your browser. Not a single byte goes to Nadoo's servers.

Up to expert-level diagnosis

PKCS#7 padding errors
and beyond

Catches digital signature encoding errors most tools miss, plus font embedding issues, PDF/A violations — informed by Nadoo's own e-contract operations.

Frequently asked questions

If we 'fix' a digital signature padding error, the PDF looks normal but the signature bytes change — invalidating the signature. To prevent legal disputes from users unaware of this, we deliberately diagnose only.

Want to never deal with
broken PDFs again?

Sign with Nadoo e-contract from the start — auto-validation means zero broken PDFs. If you have 100 broken PDFs already, Nadoo is the answer.

Start e-contract free Learn about e-contract

Feature	This free tool	Nadoo e-contract
PDF diagnosis	✓	✓ Auto pre-validation
Auto-apply digital signatures	—	✓ PKI-based
Generate valid PDFs from start	—	✓ In-house engine
Multi-signer integrated mgmt	—	✓
Legal audit trail	—	✓ Permanent