What signature validation actually checks
A PDF digital signature answers two different questions, and it’s easy to conflate them. The first is integrity: has the signed content changed since it was signed? That’s a cryptographic hash comparison — deterministic, and something localdobe can check fully on your device. The second is identity trust: is the certificate that produced the signature actually issued to who it claims, by an authority you trust? That check depends on validating a certificate chain against a trust store — the list of certificate authorities your operating system or browser trusts.
localdobe checks both, on your device. Integrity is a pure hash comparison. For identity trust, the tool bundles the same publicly published trust list that Adobe Acrobat itself uses — the Adobe Approved Trust List — and verifies the signer’s certificate chain against it locally, so a document signed through a recognized authority gets a real “valid” verdict without your file going anywhere. The one thing that genuinely requires a network call is revocation (checking whether a certificate was cancelled after being issued); that check is skipped and clearly noted in the report rather than silently assumed.
Why local checking matters for signed documents
Documents worth signing — contracts, notarized filings, signed invoices — are exactly the documents you don’t want sitting on a third-party server. Most “free” online signature checkers upload your PDF to validate it, which means a contract’s full contents (and its cryptographic signature) pass through someone else’s infrastructure before you get an answer. localdobe validates and strips signatures using a PDF engine that runs entirely inside your browser tab: your document is never transmitted, logged, or stored anywhere.
Want the details? Read how PDF digital signatures actually work and what actually happens to your files on online PDF tools.
Frequently asked questions
What does “integrity intact” mean?
The signed portion of the document hasn’t been modified since signing. That’s the cryptographic core of a PDF signature.
How can it verify who signed, without the internet?
The tool bundles the same publicly published trust list Adobe Acrobat uses (the AATL) and verifies the signer’s certificate chain against it on your device. Only revocation checks — whether a certificate was cancelled after issue — need the internet, and those are skipped and noted.
Does removing a signature change the document?
No. It strips the signature object; page content is untouched. The output is simply no longer signed.
Is my contract uploaded anywhere?
No — validation runs entirely in your browser. Ideal for documents too sensitive for online tools.
Can I validate a PDF signature online?
Yes — and unlike most “online” validators, it happens in your browser. Integrity is checked cryptographically on your device, and the signer’s certificate is verified against Adobe’s AATL trust list locally. Nothing is uploaded.