# Password protect PDF

> Browser-only file conversion. Selected files are processed on this device and are not uploaded to a conversion server.

Source: https://localconverter.tech/protect-pdf

Create an AES-256 encrypted PDF that asks for a password when opened. Choose a nonempty password for a working unprotected source, then verify it in a PDF reader after downloading. Keep the password through your own appropriate storage process, since this tool does not provide a password recovery workflow.

## Useful tasks

- Create a password-opening PDF copy
- Prepare a protected document for a controlled handoff
- Add encryption to an existing PDF attachment

## Steps

1. **Choose an unprotected PDF**: Add one working PDF with up to one hundred pages. If it is already locked, first create a readable copy using its known open password.
2. **Enter an open password**: Choose a nonempty password of up to 256 characters. Enter it for this operation and keep it through your own password-storage process rather than embedding it in filenames.
3. **Create the protected copy**: Run Process document to encrypt the new PDF using AES-256. Wait for output verification before downloading the protected result for your intended handoff.
4. **Verify opening behaviour**: Download the PDF and open it in a compatible reader. Check that the chosen password opens the document and retain access to the source when a different copy is needed.

## Settings

- **Open password**: Enter the document password only for this operation. It is sent to the local worker, omitted from public job details and never included in a download filename. Keep a separate safe copy if you are setting a new password.

## A protected document handoff

A project document needs a password-opening copy for a specific recipient. Choose a new password, create the protected PDF and test it in a reader. Keep the password in your own approved storage and provide it through the intended handoff process.

## Check the result

Choose a file, adjust the settings, then download the result. Encrypts with AES-256. Choose a nonempty password and keep it safe. Open the saved output in the app or workflow where you plan to use it. Check one representative result before repeating the same settings with more files. The original files stay unchanged.

## Limits

- Files are processed on this device. Browser memory and engine-specific limits apply. Save results before reloading.
- Encrypts with AES-256. Choose a nonempty password and keep it safe.
- Upload one file with a combined size of at most 100 MB. The completed output must fit within 200 MB.
- Files are checked by the local engine; a matching filename alone is not proof of valid contents.
- Selections and completed jobs stay available while you navigate inside this tab. Use My files to revisit results. Reloading or closing the tab clears the workspace; download results you want to keep first.

## Questions

### Which encryption is used?

The tool creates an AES-256 encrypted PDF with the supplied open password. Test the output in the recipient’s PDF reader, since the ability to open an encrypted document depends on that application supporting the resulting PDF encryption.

### Can the password field be empty?

No. The operation requires a password between one and 256 characters. Choose a value you can retain appropriately, and avoid putting passwords into document titles, example text or filenames that may be displayed elsewhere.

### Does the tool recover a forgotten password?

No. Protection creates a new encrypted copy, and the separate unlock workflow requires the correct known password. Keep your source document and password accessible through your own process if you need to revise or unlock the result later.

### Can I protect an already locked PDF directly?

The protection workflow expects a source it can open without a password. Use the known-password unlock tool to create an unprotected copy first, then protect that copy with the intended new open password.

### Does Password protect PDF upload files to another service?

Processing runs in this browser, on your device. Files and pasted input are not uploaded to a conversion server. The website and required engine assets must load first; large operations depend on available device memory.

### Can I continue after changing pages?

Selections and completed jobs stay available while you navigate inside this tab. Use My files to revisit results. Reloading or closing the tab clears the workspace; download results you want to keep first.

## Related guides

- [Merge PDF](https://localconverter.tech/merge-pdf.md)
- [Split PDF](https://localconverter.tech/split-pdf.md)
- [Images to PDF](https://localconverter.tech/images-to-pdf.md)
- [Reorder PDF pages](https://localconverter.tech/reorder-pdf.md)
- [PDF to TXT](https://localconverter.tech/pdf-to-txt.md)
- [PDF to PNG](https://localconverter.tech/pdf-to-png.md)