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Protect PDF Online Free – Password Protect & Encrypt PDF Files

Add 256-bit AES password protection to any PDF. Set an open password and restrict printing, copying, or editing permissions. Secure and free - no account required.

Select a PDF to protect

Drag & drop your PDF here, or click to browse

PDF files only · Up to 100 MB

How it works

Protect a PDF in 3 simple steps

No software to install. Works on any device with a modern browser.

01

Upload your PDF

Click "Select PDF file" or drag and drop. SupaPDF renders a preview of the document immediately so you can confirm it's the right file.

02

Set a password & permissions

Enter an open password and confirm it. Optionally restrict printing, copying, annotations, or modifications using the permission toggles. Add an owner password if you want to manage permissions separately.

03

Download your protected PDF

Click "Protect PDF". The file is encrypted server-side and returned immediately. Anyone who opens it will be asked for the password.

Why SupaPDF

Everything you need to protect PDFs

Used by developers and teams worldwide to secure PDFs reliably and at scale.

128-bit AES encryption

SupaPDF applies industry-standard 128-bit AES encryption. The password is never stored - only the encrypted output is returned to you.

Granular permissions

Control exactly what recipients can do: print, copy text, annotate, fill forms, or make modifications - independently toggleable.

Owner & user passwords

Set a separate owner password to control permissions without sharing the open password - useful for distributing documents while retaining administrative control.

Full developer API

Automate PDF protection in your own application. Pass the password, owner password, and permission flags in a single REST call.

Developer API

Protect PDFs programmatically

Use protect_pdf with a password and optional permission flags. All boolean flags default to the values shown below.

curl -X POST https://api.supapdf.com/v1/jobs \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "tag": "protect-pdf-job",
    "tasks": {
      "upload-1": { "operation": "import/upload" },
      "protect-0": {
        "operation": "protect_pdf",
        "input": ["upload-1"],
        "password": "s3cur3P@ss",
        "owner_password": "ownerP@ss",
        "allow_print": true,
        "allow_copy": false,
        "allow_annotations": true,
        "allow_forms": true,
        "allow_modify": false
      },
      "export-result": { "operation": "export/url", "input": ["protect-0"] }
    }
  }'

Required: password - the open/user password. Optional: owner_password - defaults to password. Permission flags default: print ✓ copy ✓ annotations ✓ forms ✓ modify ✗

FAQ

Frequently asked questions

Everything you need to know about password-protecting PDFs with SupaPDF.

Ready to secure your PDF?

Free to use · No account required · Instant download