What Opcilo does
Opcilo is a document sealing and verification platform. You upload a file — an invoice, contract, certificate, receipt, or other business document — and Opcilo creates a seal: a cryptographic fingerprint of that exact file, paired with a short verification code and a public link such as opcilo.com/verify/X7F-G2K-9PX.
Anyone who opens the link sees a verification card: seal status, issuer context, and document details. Recipients do not need an Opcilo account. If someone swaps the attachment or edits the PDF after you sealed it, the seal no longer matches — the proof fails.
The problem sealing solves
Email attachments and shared drives are easy to replace. A supplier can re-send a "corrected" invoice. A contractor can swap a signed PDF for a different version. Without an independent check, you are trusting whoever last sent the file.
Document sealing answers a narrow, high-value question: is this the same file that was sealed at a known time by a known issuer? That is file integrity proof — not notarization, and not a substitute for legal advice.
How document sealing works in three steps
- 1
Upload
- 2
Seal code
X7F-G2K-9PX
- 3
Verify
✓
Upload → get a seal code → anyone opens the verification card.
The core loop is deliberately simple:
Upload and seal
You upload the document in Opcilo. The platform stores the file, computes a SHA-256 fingerprint, and issues a verification code with a shareable link.
Share the link
Send the verification URL (or code) with your invoice, contract, or certificate. Recipients open it in a browser — no login wall.
Verify integrity
The verification page shows whether the seal is active, processing, or revoked, plus document details. Recipients can confirm they are looking at the sealed record, not a swapped attachment.
Who document sealing is for
- Finance and operations teams that send invoices and want payment against the sealed version — not a swapped PDF.
- Legal and commercial teams sharing contracts or certificates where "this is the issued file" matters.
- Founders and small businesses who need a simple integrity link without deploying PKI or building a portal.
- Recipients (customers, vendors, auditors) who need to check a document without creating an account.
How Opcilo differs from e-signature, storage, and plain PDFs
Opcilo is not an e-signature tool. Electronic signature products prove who agreed to terms. Opcilo proves the file bytes have not changed since sealing. You can use both: sign for consent, seal for integrity.
A quick contrast:
| Topic | Opcilo | Other |
|---|---|---|
| E-signature (e.g. DocuSign) | Integrity seal + public verify link | Consent / signature workflow |
| Cloud storage (Drive, Dropbox) | Fingerprint + verification status recipients can check | File hosting and sharing permissions |
| Plain PDF watermark | Cryptographic seal tied to a live verification page | Visual mark that can be copied or forged |
What sealing does — and does not — guarantee
Files are encrypted at rest with AES-256 on Microsoft Azure. Each seal carries a SHA-256 fingerprint so recipients can confirm integrity. Workspace data is isolated per organization. Sign-in uses Microsoft Entra.
Opcilo is not end-to-end encrypted. Sealing and PDF processing require server-side access to file contents. We do not claim end-to-end encryption — that would be inaccurate for this product design.
Practical security properties you can rely on:
- AES-256 encryption at rest for stored documents
- SHA-256 fingerprint per seal for integrity checks
- Workspace isolation between organizations
- Microsoft Entra for authentication
- Short-lived, on-demand access patterns for sealed downloads where applicable
PDF watermark vs integrity seal for other file types
PDFs can receive a watermarked sealed output so the visual document and the verification record travel together. Other supported types — Office documents, images, CSV, CAD, video, ZIP, and more — use integrity sealing: cryptographic hash plus verified download from the seal record.
Plans and revocation
Free tier includes a limited monthly seal allowance with a watermarked footer on free seals. Pro and Team unlock higher quotas, branding options, confidential delivery, Seal Bundles, and seal revocation. A revoked seal shows a clear revoked status when someone opens the verification link.
Free recipient verification links expire after a shorter window; paid plans can choose longer access durations. Check current pricing on the Opcilo pricing page for exact limits.
Beyond sealing
Sealing is the core product loop. On the verification card, look for Document integrity, Issuer Verified after business verification (Know Your Business, or KYB — not the same as email-verified), and Identity Not checked — explained in What Opcilo proves. Opcilo also offers related workflows built on the same integrity model — described in separate Learn guides: Business Inbox (workspace receive at /app/inbox) and Recipient Wallet (distinct device tray for recipients), plus sealed invoices and Pay Now, requesting documents, Bulk Seal, recipient groups, Opcilo ID, and multi-channel notifications.
Frequently asked questions
What is a seal?
A seal is a tamper-evident fingerprint of your document. Opcilo stores the file securely and gives you a verification link anyone can open.
Do recipients need an account?
No. Verification links work for anyone. Recipients see seal status, issuer, and document details without signing in.
Is Opcilo an e-signature tool?
No. Opcilo is not an e-signature tool. Signatures prove consent; sealing proves the file has not been altered since it was sealed. Many teams use both.
Is my data end-to-end encrypted?
No. Files are encrypted at rest with AES-256, each seal has a SHA-256 fingerprint, and workspaces are isolated — but Opcilo is not end-to-end encrypted because sealing and PDF processing need server-side access to file contents.
What file types are supported?
PDFs get a watermarked seal. Office, images, CSV, CAD, video, ZIP, and more use integrity sealing with cryptographic hash and verified download.
Can I revoke a seal?
Pro and Team plans include revocation. A revoked seal shows a clear status when someone tries to verify it.