KeroTools

Protect PDF — Add a Password

Add a password to a PDF so only the right people can open it — right in your browser. Your file never leaves your device, and there are no watermarks or sign-ups.

No uploads — 100% privateRuns in your browserFree, no account needed

Drop PDF here or click to browse

PDF files only

Your file and password never leave your device

Nothing to delete later

Secure connection

Works in every modern browser

How it works

  1. 1

    Add your PDF

    Drop the PDF onto the page or click to browse and select it.

  2. 2

    Set a password

    Type the password that will be required to open the file.

  3. 3

    Protect & download

    Press Protect — the encrypted PDF is built in your browser and downloads instantly.

Why use this tool

Password protection

Encrypt the PDF so it can only be opened with the password you set.

Private by design

The file is encrypted locally in your browser and never uploaded to a server.

You keep the password

The password is set on your device — we never see it or store it.

No watermark

Protection adds security, not marks — your pages stay clean.

Free & unlimited

No account, no trial, no per-file charges — protect as many PDFs as you need.

Works on any device

Phone, tablet, or computer — it runs in the browser you already have.

What does protecting a PDF do?

Protecting a PDF encrypts it and attaches a password, so anyone who tries to open the file is asked for that password first. Without it, the document simply will not display — its contents stay scrambled. This is the standard way to keep a sensitive document safe when it has to be emailed, uploaded, or stored somewhere you do not fully control. Because this tool runs entirely in your browser, both the file and the password stay on your own device; nothing is uploaded, so the very thing you are trying to protect is never exposed in the process.

When should you protect a PDF?

Add a password whenever a PDF contains something you would not want a stranger to read. People protect bank statements and tax documents before emailing them, businesses lock contracts and internal reports, and anyone sending an ID scan or medical record adds a password as a basic safeguard. It is also wise before uploading a file to shared storage. Share the password through a separate channel — a text or a call rather than the same email — so the file and its key never travel together.

How to get the best results

Choose a strong password: long, unique, and not something guessable like a birthday. Because there is no way to recover a lost PDF password, store it somewhere safe, such as a password manager, before you send the file. Send the password to the recipient separately from the document. And keep an unprotected copy of the original in a secure place, so you are never locked out of your own file if the password is forgotten.

Limitations to be aware of

A password stops someone from opening the file, but it is only as strong as the password you choose — a weak password is easy to guess. There is no “forgot password” for a PDF, so a lost password means a lost document unless you kept an original. Protection secures the file at rest and in transit; once a trusted person opens it, they can read and, depending on the PDF, copy its contents. For most everyday privacy needs, though, an open-password is exactly the right level of protection.

Common mistakes and how to avoid them

The most serious mistake is sending the password in the same email as the file, which defeats the purpose — use a separate channel. Another is choosing a weak, memorable password; make it strong and store it in a manager. People also sometimes protect their only copy and then forget the password, locking themselves out — always keep a secure original. Finally, do not assume a protected PDF is safe to leave on a public computer; the protection is for the file, not for a device someone else can access.

Using it on mobile and desktop

On a computer, drag a sensitive PDF onto the page, set a password, and download the protected version ready to email — all without the file ever leaving your machine. On a phone, protect a document before sharing it in chat or uploading it to a portal; everything runs locally. Because there is no app to install, the same link works on every device, and the protected file prompts for the password in whatever reader the recipient uses.

Why protect here instead of another site?

It is worth pausing on the irony of most online “protect PDF” tools: they ask you to upload the very file you are trying to keep private to their servers. This tool never uploads anything — the encryption happens inside your browser, and the password is set on your device and never transmitted. There are no watermarks, no account, and no limit on how many files you protect. For a task that is entirely about privacy, doing it locally is the only approach that makes sense.

How it compares

FeatureThis toolTypical online PDF tools
File uploaded to a serverNever — encrypted in your browserUsually uploaded
Password sent over the networkNeverSometimes
Standard PDF passwordYesYes
Watermark on outputNoSometimes
Account or sign-upNot requiredOften required
PriceFreeFree / paid tiers

Features

Standard PDF encryption

Uses the password protection built into the PDF format, opened by any reader.

Open-password (user password)

Requires the password before the document will display at all.

Set on your device

The password never travels over the network — it stays with you.

Works everywhere

The protected file prompts for the password in any standard PDF viewer.

No installation

Nothing to download or install — it works on the web page.

Offline-capable

Once the page has loaded, protecting works even without internet.

Arabic & RTL friendly

Full interface in eight languages, including right-to-left Arabic.

Secure by default

Served over HTTPS, with no file tracking and no third-party upload.

Who uses it

Anyone sharing financial documents

Lock a bank statement or tax return with a password before emailing it.

Businesses

Protect contracts and internal reports so only intended recipients can open them.

Healthcare & legal

Add a password to sensitive records before they leave the office.

Everyday users

Password-protect an ID scan or private document — encrypted on their own device.

Frequently Asked Questions

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