Proview

Privacy policy

Last updated: October 12, 2026

Proview is an open-source desktop application maintained by Emanuele Longo. This policy describes the application and this project website.

Local documents and signatures

Proview opens and edits documents on your computer. Document rendering, image processing and OCR run locally. The signature library is stored locally. The cloud synchronization feature does not upload the documents you open, their pages or general application preferences.

Optional Google Drive synchronization

Google Drive synchronization starts only when you choose to connect it from the signature library’s Cloud sync settings and authorize Proview in your browser. Proview uses Google authorization for this feature; it does not require a Google account to view or edit local files.

Proview requests https://www.googleapis.com/auth/drive.file. This allows access to files created by Proview or explicitly authorized for it, rather than general access to all your Drive files. Proview reads relevant file and folder metadata and creates, reads, updates and retires synchronization files in the configured archive, which defaults to proview/signatures.

The archive contains signature artwork, signature names and related identifiers, timestamps, synchronization indexes and deletion records. These data are used to synchronize your signature library between computers, merge changes and prevent deleted entries from returning during ordinary synchronization. Superseded signature payloads and validated legacy synchronization files may be moved to Drive’s trash.

Authorization credentials and storage

Google issues access and refresh tokens so Proview can synchronize without asking you to sign in each time. Proview stores saved tokens in your operating system’s credential store. If persistent credential storage is unavailable, a connection may last only for the current session. Folder identifiers and non-secret connection settings are kept in local application preferences.

Google Drive data passes directly between your computer and Google’s APIs over HTTPS. The signature sync feature does not send your Google tokens or signature archive to a server operated by the Proview maintainer. Your archive is stored in your own Google Drive account; Google’s services and storage policies also apply. Proview does not add a separate application encryption layer to the signature archive.

Use and sharing of Google data

Proview uses data obtained through Google APIs only to provide the signature synchronization feature described here. It does not sell that data, use it for advertising, transfer it to data brokers or use it to train AI models. The application does not provide the maintainer with access to your archive.

Proview’s use and transfer of information received from Google APIs will adhere to the Google API Services User Data Policy, including the Limited Use requirements.

Disconnecting, revoking access and deleting data

Stop synchronization: choose Disconnect in Cloud sync. This stops synchronization and removes saved credentials and connection settings when the system credential store is available. A credential-removal failure is reported by the app. Local signatures and the remote archive remain.
Revoke Google authorization: remove Proview’s access from your Google Account’s third-party connections. Disconnecting in Proview does not itself revoke the Google authorization.
Delete an individual signature: delete it in the signature library. When connected, the deletion is synchronized; a small deletion record remains to reconcile other devices. Offline changes are queued until a later synchronization.
Remove the complete cloud archive: disconnect all Proview installations using it, then delete its folder in Google Drive. Files in Drive’s trash and any revisions are subject to Google’s retention controls; use Drive’s controls to remove retained copies. Local copies remain on each computer and must be removed there separately. Reconnecting an installation that still has local signatures may upload them again.

Local signature data remains until you remove it. Cloud signature data remains in your storage until it is deleted or retired by synchronization. Proview has no automatic expiration period for the current archive. Deletion records do not contain signature artwork.

Optional S3 storage

If you choose S3 instead of Google Drive, Proview sends signature data directly to the endpoint and bucket you configure. Access keys are stored in the operating system’s credential store when available. Your storage provider’s policies apply. Disconnecting preserves local signatures and remote objects. Switching providers does not erase the previous archive.

Website and support

This website uses no analytics scripts, advertising scripts, cookies or contact forms. It is hosted by GitHub Pages. GitHub logs visitors’ IP addresses for security purposes; see the GitHub Privacy Statement. Following links to GitHub or Google takes you to services governed by their own policies.

If you contact the maintainer through GitHub issues, your message and any attachments may be public. Share only information needed for your request, and never upload private documents, signature artwork or authorization credentials.

Contact and changes

For privacy questions, contact Emanuele Longo at longo.emanuele@gmail.com. Contact information and messages you send are used to respond to your enquiry. Please do not include authorization credentials or unnecessary sensitive attachments. This page will be updated when the described data practices change.