Seal PDF
Add a tamper-evident seal so anyone can check the PDF hasn’t been changed.
Select a PDF file
or drop them anywhere on this page
Processed on your device. Never uploaded.
Processing on your device. Nothing is uploaded.
Add your files
Choose or drop a file from your device.
Adjust the options
Set the options in the side panel, or keep the defaults.
Download the result
Save it, or send it straight on to another Paperwing tool.
ISO gap assessment tool
About Seal PDF
Seal PDF stores a SHA-256 fingerprint of the finished file inside the file, and can add a small note on the last page. Anyone can later check it with Verify sealed PDF: any change, even a single character, breaks the seal. Keep the fingerprint code to confirm it is the copy you sealed. It is not a legal digital signature.
Why use Paperwing
- Private by design Files are processed in this tab with JavaScript. Nothing is sent to a server, so contracts and medical records stay with you.
- No queues, no waiting There is no upload step, so a 50-page merge finishes about as fast as your device can read the files.
- Chain your tools Finished merging? Send the result straight to Compress, Sign or Page numbers without downloading in between.
- Works offline, installs as an app Open a tool once and it keeps working without internet. Install Paperwing to open PDFs straight from your computer.
Frequently asked questions
Is Seal PDF free?
Yes. Seal PDF is free to use, with no sign-up, no watermark and no daily limit.
Are my files uploaded to a server?
No. Paperwing processes your files inside your browser, on your own device. They are never uploaded, and they are cleared from memory when you close the tab.
Does it work on my phone?
Yes. Paperwing works in any modern browser on Windows, Mac, Linux, Android and iPhone, with nothing to install.
Is there a file size limit?
Each file can be up to 300 MB. Very large files depend on your device's memory, so a computer handles them faster than a phone.