Four questions, four jobs
People reach for a familiar product name when they hear “prove this file.” The products in that sentence are doing different work. Adobe is how you create or edit a PDF. Dropbox is where the file lives and who in the workspace can open it. DocuSign is who agreed. Opcilo is whether the copy in someone’s hands is the sealed file, and who sealed it.
- 1
Create or edit a PDF
Adobe and similar tools. Question: how do I make or change this PDF?
- 2
Store and share the file
Dropbox and similar tools. Question: where is the file, and who in the workspace can open it?
- 3
Sign it
DocuSign and similar tools. Question: who agreed?
- 4
Prove it's the exact file, and who sealed it
Safe pathOpcilo. Anyone with the link can check, with no account, for any file you seal.
Opcilo sits after create, store, and sign. The check is independent, needs no recipient account, and applies to any file you seal.
What Adobe, Dropbox, and DocuSign already do
Adobe Acrobat and related PDF tools create and edit PDFs. When a PDF carries a digital signature or a certification, a reader that validates signatures — Acrobat included — can show that the PDF changed afterward. That is tamper-evident output for that PDF, when the signature or certificate is present.
Dropbox stores and shares files. It keeps version history for files stored there, and business plans can expose an admin audit log of activity inside Dropbox. That trail describes copies that stayed in Dropbox. A file that left as an email attachment is outside it.
DocuSign records agreement. A completed envelope includes a certificate of completion and an audit trail of the signing events. The finished PDF can carry a digital signature so a later edit is visible to a reader that checks it. That answers who agreed, and it can show that the signed PDF changed. It does not, by itself, give every later reader a check that works with no login for any file.
What Opcilo adds
Opcilo’s difference is an independent check any recipient can do with no login, for any file you seal. They open the verification link, see who sealed it, and can compare the file in their hands to the sealed fingerprint. The same check covers a PDF, a spreadsheet, an image, a ZIP, or another supported file — including a file that was created in Adobe, stored in Dropbox, or signed in DocuSign.
Same moment in a workflow, different question. Other tools can produce tamper-evident or audit-trail output. Opcilo checks the file the recipient is holding.
| Topic | Opcilo | Other |
|---|---|---|
| Adobe — create or edit a PDF | Independent check that the file in hand matches the seal, with no login | Create and edit the PDF, and show a later change when a signature or certificate is present |
| Dropbox — store and share the file | A public verification link for the sealed bytes, including copies that left the folder | Version history and an admin audit log for files that remain in Dropbox |
| DocuSign — sign it | Proof the file bytes match what was sealed, for any file you seal | Agreement, a certificate of completion, and an envelope audit trail |
Common objections
We already sign everything in DocuSign
Keep signing. The signature records consent inside the envelope. Seal the completed file when someone who was not in that envelope — or who only has the PDF — needs to confirm they are holding the sealed bytes. Many teams do both.
We already keep the file in Dropbox
Keep the folder. Version history and the admin audit log answer questions about files inside Dropbox. The person who received an attachment may have no access to that log. The verification link travels with the copy they actually have.
Acrobat already warns me
That warning is real for a PDF that carries a signature or certificate, opened in a reader that checks it. An unsigned PDF, a Word file, or a ZIP does not get the same warning. Opcilo’s check does not depend on the recipient owning Acrobat.
Opcilo sits after those tools
Create the file, store it, sign it, then seal the version you are sending. Opcilo does not replace Adobe, Dropbox, or DocuSign. For the sealing loop itself, see what document sealing is. For why the accurate word is tamper-evident, see why we say tamper-evident.
Frequently asked questions
Does Opcilo replace Adobe, Dropbox, or DocuSign?
No. Those tools create or edit a PDF, store and share the file, or record agreement. Opcilo sits after them and checks that the file in hand is the sealed file.
Can those tools already show that a file changed?
Yes, in their own records. A certified or signed PDF can show a later edit. Dropbox keeps version history and, on business plans, an admin audit log. DocuSign keeps a certificate of completion and an envelope audit trail, and the finished PDF can carry a digital signature. Opcilo’s difference is an independent check any recipient can do with no login, for any file you seal.
Does the recipient need an account?
No. The verification link opens without a login. The recipient can see who sealed the file and check the copy they are holding.