PAdES Studio

macOS app for PDF signing

PAdES Studio

Download on the Mac App Store

Sign and verify PDF documents locally on macOS using digital certificates available in Keychain. The app writes a standard PDF signature field and supports visible signatures, RFC 3161 timestamping, and PAdES-oriented validation data.

PAdES-B-B to B-LTAmacOS KeychainLocal processingEU Trusted Lists
Digitally signed PAdES-B-LT
RFC 3161 timestamp

Built for real PDF digital signatures, not just a visible stamp.

PAdES Studio writes signatures as incremental PDF updates so the original document bytes are preserved and existing signatures can remain verifiable.

Keychain signing

Select a signing identity from macOS Keychain, including supported CryptoTokenKit smart cards, and sign with a private key that stays in Keychain or on the token.

Visible signature

Add an optional page area, signature image, signer name, and signing time without changing the cryptographic signature model.

Timestamping and LTV

Use RFC 3161 timestamps and embed certificates, OCSP responses, or CRLs in the PDF Document Security Store when available.

Signature inspection

Review signature status, certificate chains, timestamps, DSS/VRI material, EU Trusted List evidence, and detected or validated PAdES profiles.

Multiple signatures

Add another signature as a new document revision. Existing signatures are not rewritten and remain independently verifiable.

Local documents

PDF files are not processed on the developer's server. Network access is used only for optional TSA, OCSP, or CRL requests.

From opening a PDF to a verifiable signature.

The app supports everyday signing as well as archival workflows where timestamps and validation data matter.

Step 1

Open a PDF

Open a document from the File menu, Open Recent, or by dragging it into the app window.

Step 2

Select an area

Mark a place on the page for a visible signature, or skip selection for an invisible digital signature.

Step 3

Choose a profile

Select the identity, metadata, PAdES profile, timestamp server, and LTV options required by the document.

Step 4

Sign and verify

Save the signed copy, then inspect the signature status, certificates, and validation notes.

Supported PAdES-oriented outputs.

Higher profiles need more external data. The app reports when timestamps or long-term validation material cannot be obtained.

PAdES-B-BBaseline detached CAdES signature embedded in a PDF signature field.
PAdES-B-TA signature with an RFC 3161 signature timestamp from the configured TSA.
PAdES-B-LTDSS/VRI material with certificates, OCSP responses, or CRLs when the certificate chain provides them.
PAdES-B-LTAAn archive document timestamp covering the revision after the DSS/VRI update.
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Support

Reference notes from the user guide for supported standards, limitations, troubleshooting, safety, and common questions.

Supported formats and standards

  • PAdES Studio creates PDF signature fields with detached CMS/CAdES signatures.
  • Supported profiles are PAdES-B-B, PAdES-B-T, PAdES-B-LT, and PAdES-B-LTA.
  • RFC 3161 timestamps and DSS/VRI validation material are embedded when available.
  • Optional EU Trusted Lists can use fresh, signature-verified EU LOTL and national trusted-list CA/QC matches as a technical trust source, while never claiming legal qualified-signature status.

Limitations

  • PAdES Studio supports macOS 13.0 or later only.
  • Signing requires a certificate and private key available through macOS Keychain or a supported CryptoTokenKit smart card or hardware token.
  • PKCS#11-only tokens, some complex PDF structures, and signature removal are not currently supported.
  • The app does not decide whether a signature is legally qualified.

Troubleshooting

  • If no identity appears, check that the certificate has a private key, is not expired, and allows digital signatures.
  • If timestamping or LTV fails, verify the TSA URL, network access, certificate chain, OCSP endpoints, and CRL URLs.
  • If a file verifies as modified, compare it with the original and inspect Validation notes.

Safety notes

  • Keep the original unsigned PDF whenever possible.
  • Verify signed output before distribution, ideally also with an independent validator for important documents.
  • Choose a timestamp authority appropriate for your compliance requirements.
  • Protect your signing certificate, token, PIN, and private key carefully.

FAQ

Is a signature produced by PAdES Studio legally binding?
PAdES Studio produces technically standard PAdES signatures. Legal effect depends on the certificate, trust provider, signing environment, TSA, jurisdiction, and document context.
Can I sign with a smart card or hardware token?
Yes, when the token exposes the signing certificate through macOS Keychain/CryptoTokenKit. PAdES Studio lists the certificate without asking for the PIN; the card or token asks for PIN or approval only when you sign. PKCS#11-only tokens are not currently supported.
Can I sign an encrypted or locked PDF if I know the password?
Not in the current version. A password can theoretically unlock opening or owner permissions, but PAdES Studio does not rewrite encrypted PDFs or preserve PDF encryption for newly added signature objects. Save an unrestricted copy first and sign that copy.
Does PAdES Studio need an internet connection?
Basic signing and local verification can work offline. Internet access is needed when you use an RFC 3161 timestamp server, collect OCSP or CRL material for long-term validation, or enable EU Trusted Lists so the app can download or refresh EU LOTL and national trusted-list data.
Why would I leave EU Trusted Lists disabled?
EU Trusted Lists are useful when you need that trust source, but they are intentionally optional. The app must download, cache, parse, freshness-check, and signature-verify EU LOTL and national trusted-list XML before using them, then match trusted-service evidence against certificate chains. That is computationally more expensive than local or system trust checks and can slow signature validation, so it makes sense to keep EUTL disabled unless you need it.
Where are my signing settings stored?
They are stored locally in app preferences, including certificate fingerprint, timestamp URL, profile, metadata, visible-signature settings, and explicitly trusted local root certificates. PAdES Studio does not store private keys, PINs, passwords, or PDF document contents; signing keys remain in macOS Keychain or on the smart card or hardware token.
Which TSA should I use?
Use any RFC 3161 compliant TSA you trust. Regulated workflows may require a specific accredited TSA.
Can I remove a signature from a signed PDF?
No. PAdES Studio does not remove signatures from signed PDFs.
Can I add a visible signature when I re-sign a signed document?
Yes, if the selected rectangle is large enough. Existing signatures are preserved.
Why does the strict validator show a lower profile than the detected one?
The strict validator requires DSS, VRI, and archive timestamp material to be complete and verifiable, not merely present.
Can I use PAdES Studio to verify a signature made by another tool?
Yes. The Verify button can inspect signatures created by other PDF signing tools.
What happens when I open a document from Finder while another one is loaded?
The new document replaces the active document in the window. Source files are not modified.

For other questions or feedback, contact us at: info@cloudmakers.eu

Documents stay local.

PAdES Studio does not use a developer-operated server to process PDFs. Timestamping and LTV may contact only endpoints you configure or endpoints published in certificates.

Read the Privacy Policy