OpenSig

A DIGITAL PEN ON YOUR PHONE
OpenSig is the simple, private way to sign documents and create independently verifiable proofs for any file. No complex workflows and no file uploads.
Sign PDFs, images, videos, design files, code, ZIPs and more. Add optional encrypted notes to record purpose, intent or context. Use OpenSig to approve documents, lock in deliverables, protect your intellectual property, and timestamp important work.
WHY OPENSIG?
• Private by design – your documents never leave your device
• Works with any file type and size
• Create permanent, tamper-proof proofs
• Add optional encrypted annotations such as purpose or message
• No accounts, no uploads, no monthly subscription
• Independent verification: anyone with the file can verify your proof
WHAT YOU CAN DO
• Sign and approve documents
• Prove authorship of creative work
• Timestamp drafts, designs and revisions
• Protect ideas, pitches and deliverables
• Verify file integrity before handoff
• Add short encrypted notes or URLs to your signature
• Share proofs with clients, collaborators or auditors
No uploads. No central storage. Just simple, verifiable signing you control.