Check the digital signature (DSC) in a PDF: who signed it, when, and whether the file was changed after signing. Works for Form 16, GST invoices and government certificates. Your PDF never leaves your device.
Form 16, GST e-invoices, gazette notifications and many certificates are signed with a digital signature (DSC). This tool tells you who signed the PDF, when, whether the certificate comes from a licensed Indian provider, and whether anyone changed the file after it was signed.
Is my PDF uploaded? No. The signature is checked inside your browser. Your PDF never reaches our server, which matters for documents like Form 16 that contain your PAN and salary.
Why does Adobe Reader say “Signature Validity Unknown”? Adobe Reader does not trust India's root certificate (CCA India) by default, so it cannot tell who issued the signer's certificate. This tool already includes the CCA India root certificates, so it can check the full chain.
What does “changed after signing” mean? The bytes of the document no longer match what was signed. Someone edited the file after it was signed, so its contents cannot be trusted.
Does the tool go online at all? Only when a PDF is missing the certificate provider's own public certificate. Then the tool asks for that one public file, from the address written inside the signer's certificate (just like PDF readers do). Only that address is sent, never your PDF or its contents.
Is a scanned signature a digital signature? No. A picture of a signature is not a digital signature. A digital signature is a certificate-based seal inside the PDF that this tool can check.
The certificate has expired. Is the signature still valid? Yes, if the certificate was valid on the day the document was signed. Certificates usually last one to three years, so older documents often show an expired certificate.
Full guide: how to verify the digital signature on Form 16 or any PDF.
Other tools: Sign PDF, Protect PDF, Mask Aadhaar & PAN, Compress PDF.