A file that ends in .p7m.p7m, or a .p7m that carries several names, is a multi-signature P7M: more than one person signed the same document. This guide explains how multiple signatures work as a colour-coded story — nested envelopes, parallel signatures and countersignatures — and shows how to open every layer for free, in your browser, on any device.
The colour code of this guide
- 🟦 Blue — the envelope. Each .p7m layer that wraps the document. In a multi-signature file there can be more than one.
- 🟩 Green — the first signature. The seal of the first signer.
- 🟪 Purple — every additional signature. The seal of the second, third or fourth signer.
- 🟨 Yellow — the certificates. One per signer: who signed and which authority vouches for them.
- 🟧 Orange — the document. The real file at the centre: a PDF, an XML invoice, a Word file or an image.
- 🟥 Red — a warning. A mistake to avoid or a case that needs extra care.
Why a file gets more than one signature
One signature is not always enough. Typical cases: a contract that both parties must sign, a board resolution signed by several directors, a tender file signed by a legal representative and a technical manager, or an invoice that an accountant approves before the owner signs it. Each person adds their own seal, and each seal stays valid only if the document underneath does not change.
Three ways to sign more than once
- 🟦 Nested signatures (serial). The second signer signs the whole signed file, so the name grows: contract.pdf.p7m becomes contract.pdf.p7m.p7m. Every signer adds one envelope, like the skins of an onion.
- 🟩 Parallel signatures (co-signing). Several signers sign the same document side by side. The result is a single .p7m that contains several signatures and several certificates.
- 🟪 Countersignature. One signer signs another signer's signature, for example to confirm or approve it. It lives inside the same envelope.
The extension alone does not always tell you which type you have: a parallel file has one .p7m and many signers, a nested file shows the layers in the name.
The story: three signers, one document
🟧 Document ➜ 🟩 Signer 1 ➜ 🟪 Signer 2 ➜ 🟦 Outer envelope
1. 🟧 The document is ready. Everyone agrees on contract.pdf. From now on nobody may change a single character.
2. 🟩 The first signer seals it. Their signature and certificate are wrapped around the document: contract.pdf.p7m.
3. 🟪 The second signer signs the envelope. They sign the whole signed file, so a second layer appears: contract.pdf.p7m.p7m.
4. 🟦 You receive the outer envelope. To read the document you peel the layers off in reverse order: the last signer's envelope first, the first signer's envelope next, and finally the 🟧 document appears.
Opening a multi-signature P7M means removing every envelope until only the orange document is left.
Open a multi-signature P7M in 3 moves
1. 🟦 Save the file. Download the attachment to your device. Do not open it from the e-mail preview.
2. 🟩 Load it in the viewer. Go to P7M Viewer — Open .p7m and drag the file onto the page or tap Choose File.
3. 🟧 Read or download. The viewer removes all the signature envelopes automatically and returns the original document.
No installation, no Java, no account. A single file is free, and the processing runs in your browser.
How many signatures does my file have?
- 🟦 Count the endings. Every .p7m at the end of the name is one nested layer: report.pdf.p7m.p7m has two.
- 🟩 Do not trust the name alone. A parallel file can carry many signers under a single .p7m, and some programs shorten names.
- 🟥 Still ends in .p7m after opening? Then there was another envelope inside. Open the result again, or use a tool that removes every layer at once.
Check every signer, not just the first
Each signature has its own certificate, its own signing date and its own validity. When you need to be sure who signed, check them one by one: the signer's name, the authority that issued the certificate, the date, and whether a timestamp is present. Our guide on how to verify the digital signature of a .p7m file shows what to look at, and how CAdES signatures work explains the format behind them.
Open a multi-signature P7M on every device
- 🖥️ Windows 10 and 11: any browser works. To save the result as PDF use Ctrl + P → Save as PDF.
- 🍎 Mac: Safari, Chrome or Firefox. Use ⌘ + P → Save as PDF.
- 🤖 Android: the browser, or the free P7M Viewer app from Google Play.
- 📱 iPhone and iPad: open the site in Safari, tap Choose File and pick the file from Files or iCloud.
Mistakes to avoid
- 🟥 Stopping after the first layer. If the result still ends in .p7m, keep going.
- 🟥 Renaming the file to .pdf. The envelopes stay in place and the file may look corrupted.
- 🟥 Editing the document. Any change, even a comma, breaks every signature. If something must change, all the signers have to sign the new version.
- 🟥 Assuming the order does not matter. In nested files the last signer sits on the outside and the first one on the inside.
- 🟧 Dozens of files? Use Batch Open to extract many P7M files into one ZIP.
- 🟦 Need to create a signed envelope? Convert PDF, Word or XML to .p7m.
Privacy: your document stays with you
Processing happens in your browser, so the document is not sent to a server. For contracts, resolutions and confidential files this is the safest option.
Frequently asked questions
What is a multi-signature P7M file? It is a .p7m file signed by more than one person, either with nested envelopes (.p7m.p7m) or with several signatures side by side.
How do I open a .p7m.p7m file? Load it in P7M Viewer. It removes every envelope and returns the original document.
Why does my file still end in .p7m after opening it? Because it contained another signature envelope. Open the result again, or use a viewer that removes all layers at once.
Does the order of the signatures matter? In nested files yes: the last signer is the outermost layer. In parallel signatures the order is not a matter of layers.
Can I add a signature without breaking the others? Only by signing the finished file as a new outer layer or as a parallel or countersignature made with signing software. Editing the document invalidates all signatures.
Is my file uploaded to a server? No. It is processed in your browser and stays on your device.
In summary
A multi-signature P7M is a 🟧 document inside several 🟦 envelopes, each sealed by a different signer. Save the file, load it in P7M Viewer, and every layer is removed for you — free, private and on any device.
