Sello: Sign PDFs
Productivity
Only for Mac
$4.00
Mac
A lightweight, native alternative to Autofirma
Sello signs PDFs with a digital certificate in macOS Keychain. Open a document, choose your certificate, place an optional visible signature, and save.
• Sign locally: documents are not uploaded and private keys stay in Keychain.
• Use RSA or elliptic-curve software certificates, including tested FNMT certificates.
• Add signatures to already signed PDFs when their permissions allow it.
• Start from a file picker, drag and drop, or Finder’s Open With > Sello.
• Place a visible stamp or sign without one.
Sello creates PAdES Baseline B-B PDF signatures and checks local signature integrity. It does not obtain trusted timestamps, fetch revocation information, or check EU trusted lists. Acceptance depends on each procedure’s requirements.
You need an Apple Silicon Mac with macOS Tahoe 26 or later and a signing certificate with its private key installed in Keychain. Intel Macs and encrypted PDFs are not supported. DNIe and hardware tokens have not been validated.
Sello signs local PDFs. It does not handle AutoFirma browser integration, afirma: links, or standalone XAdES/CAdES files. No Sello account or subscription.
Ratings & Reviews
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The developer, Negative Epsilon, S.L., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- NEGATIVE EPSILON, S.L.
- Size
- 14.7 MB
- Category
- Productivity
- Compatibility
Requires macOS 26.0 or later and a Mac with Apple M1 chip or later.
- Mac
Requires macOS 26.0 or later and a Mac with Apple M1 chip or later.
- Mac
- Age Rating
4+
- 4+
- Copyright
- © 2026 NEGATIVE EPSILON, S.L.
