File

Encrypt & Decrypt PDF

Lock a PDF behind an open password, or strip an existing password when you already know it. The whole thing runs in your browser — the file never reaches a server. Encryption uses the AES algorithm built into the PDF spec, so without the password the content cannot be read. Typical situations: locking down a contract or quote before it goes to a client, sending payslips or medical reports by email, protecting files before they hit a cloud drive, or removing a password you have so you can compress, merge or convert the file afterwards.

  • Two modes — add a password to an unprotected PDF, or remove an existing one when the password is known
  • Open-password protection keeps the whole document unreadable until the right password is entered
  • Built-in strength meter calls out weak passwords as you type
  • Auto-detects whether the uploaded PDF is already encrypted, so the wrong mode fails fast
  • Original PDF stays untouched. Change the password and produce a new output as often as you like
  • Runs entirely in the browser. Works offline. Sensitive files never need to be uploaded
  • Pages, text, links, bookmarks and form fields all survive — encryption simply adds a layer on top
tools/Encrypt & Decrypt PDF

Drop a PDF here, or click to pick a file

Pick one PDF. Everything happens locally in your browser.

Set an open password on an unprotected PDF and download the locked copy.

Best for contracts, quotes, payslips, medical reports and anything that travels by email, chat or cloud drive. Without the password, the content cannot be read at all.

Anyone opening the PDF must enter this. Keep it somewhere safe — if it is lost, the file cannot be recovered.

Encrypting, decrypting, reading and downloading all happen in your browser. Nothing is uploaded.

Pages

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Original

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Output

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Action

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Upload a PDF and fill in the password — the result shows up here.

Command

Overview

A focused workflow for adding an open password to a PDF, or removing one when the password is already known.

  1. 01

    Open-password protection

    Set a password that the reader must enter before any content is shown. The underlying algorithm is the AES variant defined by the PDF spec — without the password, the file is genuinely encrypted bytes.

  2. 02

    Remove a password you know

    Paste the password the sender gave you and the protection layer comes off. Wrong passwords fail at load time, no half-written outputs and no quiet timeouts.

  3. 03

    Encryption state detected automatically

    As soon as the file is loaded the tool tells you whether it is already encrypted, and refuses mismatched modes upfront — encrypted files cannot be re-encrypted, unencrypted ones cannot be unlocked.

  4. 04

    Password strength meter

    A four-step indicator labels passwords as weak, fair, good or strong as you type. It nudges away from obvious dictionary words without forcing your hand.

  5. 05

    Original file stays untouched

    Both modes write a brand-new PDF. The source file never changes, so you can iterate on passwords without losing the original.

  6. 06

    Pages and form structure preserved

    Page order, text layer, links, bookmarks and form fields look identical before and after. Encryption is purely an additional layer on top of the existing document.

  7. 07

    Runs entirely in the browser

    Reading, encrypting, decrypting and downloading all happen client-side. No upload, no server logs, works offline, and the in-memory copy is released the moment the tab closes.

How to use

Pick a mode, upload the PDF, fill in the password, download — most files finish in a few seconds.

  1. 01

    Drop a PDF on the upload area or click to pick one. The tool reads the file and flags whether it is already encrypted in the file info row.

  2. 02

    Pick the mode. Unprotected PDFs go through Encrypt to gain a password; encrypted PDFs go through Remove password to drop the protection.

  3. 03

    In Encrypt mode, type the open password first. Anyone opening the new file will have to enter it. The strength bar updates live.

  4. 04

    In Remove password mode, paste the password the sender gave you or the one you saved earlier. If it is wrong, the tool fails immediately and tells you so.

  5. 05

    Hit Run. Most PDFs finish in a couple of seconds; very long files take a bit longer.

  6. 06

    Download the new PDF. The original is untouched, so you can change the password and regenerate at any time.

Details

Designed around two concrete jobs: set a password, and remove a known password — with predictable, transparent behaviour throughout.

  • Encrypt and Remove password modes in a single switch
  • Open-password encryption for the whole PDF
  • Auto-detects whether the uploaded PDF is already encrypted
  • Four-step password strength meter with live feedback
  • Show / hide toggle on every password field to avoid typos
  • Wrong-password failures surface immediately with a clear message
  • Original PDF never overwritten — iterate on passwords freely
  • Text, links, bookmarks and form fields are kept intact
  • Chrome, Edge, Firefox, Safari and Brave on desktop and mobile
  • Local-only processing, works offline, nothing uploaded

Use cases

Adding a password to a PDF you are about to share, or removing one from a PDF you have the password for — here are the situations that come up day to day.

  1. Contracts and quotes for clients

    Lock signed contracts and pricing sheets before they head to a client or supplier, then share the password by phone or a separate channel. Even if the email gets forwarded, the content stays unreadable.

  2. Payslips and HR documents

    When HR sends payslips, reviews or personnel files to individuals, set a per-employee password derived from an ID number or staff code so accidentally CC-ing a group does not leak content.

  3. Medical and lab reports

    Diagnostic reports and lab results are personal data. Encrypting them means an intercepted inbox or a forwarded message still cannot expose what is inside.

  4. Financial reports for internal review

    When sending monthly or quarterly numbers to other teams, add an open password so forwarded attachments stay unreadable without the agreed passphrase.

  5. Editing material a client sent locked

    Designers, print shops and translators often receive locked originals. With the password the client provided, drop the protection here and the file is ready for layout, edit or translation tools again.

  6. Archiving an encrypted statement

    Bank statements, flight itineraries and insurance contracts often arrive encrypted. If typing the password every time is a nuisance, unlock once and file the plain copy for long-term storage.

  7. Protecting cloud-drive backups

    Encrypt sensitive PDFs before uploading them to a cloud drive. The provider staff and any future data breach would still only see ciphertext.

  8. Sharing through team messaging

    When teams pass PDFs around in chat, send the locked file in one channel and the password through a separate, agreed-upon channel so a leaked attachment alone is useless.

  9. Legal opinions and demand letters

    Law firms protect outbound opinions and reports with an open password, then share the password through an agreed channel so the attachment alone is not enough.

  10. Pre-publication papers and manuscripts

    Researchers and authors lock drafts before sending them to reviewers or editors, reducing the chance that a forwarded attachment exposes unpublished work.

See also

If you need a fresh password before locking the PDF, generate one with Password Generator . If the material is not a PDF, or you want to wrap the whole file as ciphertext instead of keeping it directly readable as a PDF, use File Encryption . Encryption is usually the last step before a PDF goes out; if the file is still too large, run it through Compress PDF first; if every page needs a copyright or "Confidential" mark, add it with PDF Watermark before locking. More PDF utilities live in the File category.

Best practices

Encryption is just the mechanism. The real protection comes from password strength and how you hand it over. A few habits worth keeping.

  • Make the open password at least 8 characters and mix cases, digits and a symbol. Sentence-initials or random output from a password generator are far safer than common words.
  • Never send the password in the same message as the file. Pass it by phone, SMS, IM or a separate email — leak risk drops sharply when channels split.
  • Encrypt only after the PDF is finalised. Editing an encrypted PDF later means decrypting, editing and re-encrypting — manageable but tedious.
  • Store the password somewhere reliable. This tool does not know it, so a lost password means a lost file, full stop.
  • Do not encrypt PDFs that need to be previewed inline on a website or in email. Most inline viewers refuse to render encrypted files.
  • Only remove encryption from files you have rightful access to. Stripping someone else’s protection without authorisation can carry legal weight.
  • When the same PDF goes to many people, one shared password is fine; when each person needs their own copy, generate a per-recipient password so a single leak does not affect the rest.
  • For privacy-sensitive material, do the work in a private window and clear the download folder and history when you are done.

Limitations

PDF encryption has its boundaries. Knowing them up front avoids surprises.

  • Removing a password only works when the password is known. This tool never cracks unknown passwords and does not bypass DRM, certificate encryption or enterprise rights management.
  • The protection layer uses the AES variant from the PDF spec. The algorithm itself is public and sound — the actual strength depends on the password you pick. Weak ones fall to dictionary attacks in seconds.
  • Encrypted PDFs may refuse to display in older readers, default mobile previewers or inline browser viewers. A dedicated reader (Adobe Reader, Foxit, PDF Expert) usually opens them fine.
  • A handful of unusual files — certificate-encrypted PDFs, X.509 public-key protected files, Adobe LiveCycle DRM, and a few PDF 2.0 (AES-256-R6) variants — cannot be parsed or encrypted by this tool.
  • Encryption increases file size slightly. For files already near their compression limit the change is negligible; for huge scans, compress first and encrypt afterwards.
  • Existing digital signatures, annotations and bookmarks survive encryption, but some readers cannot verify signatures inside an encrypted PDF.
  • The tool processes one PDF at a time. Batch encryption means uploading and downloading file by file.
  • Passwords are not stored anywhere. They live only in the page memory and disappear on refresh — the browser will not autofill them either.

FAQ

On passwords, safety and what this tool will and will not do.

What does the open password protect?

The open password controls who can read the file. Without it, the PDF will not open and the page content stays encrypted.

Can someone crack the encrypted PDF?

The tool uses the AES algorithm specified in the PDF standard. The algorithm itself has no known practical break. Whether anyone can crack the file depends entirely on the password — a 12+ character mix of cases, digits and symbols is realistically infeasible, while "123456" or "password" fall to dictionary attacks in seconds.

Can I remove the password from a PDF someone sent me?

Yes — as long as you know the password. Paste the password the sender gave you. This tool will not try to guess unknown passwords and does not attempt brute force.

What happens if I enter the wrong password?

The load step fails immediately with a clear "wrong password" message. No time wasted and no half-written output to clean up.

Can it unlock a PDF whose password is unknown?

No. No browser-based tool can. That belongs to password-recovery software and is a different kind of work entirely.

Are my files or passwords sent to a server?

No. The tool is JavaScript running entirely inside your browser. The file never leaves your device, and the password only exists in the page memory until you refresh. You can verify this in the browser dev tools network panel.

Does the original file get overwritten?

No. The tool writes a new PDF every time. The original stays as-is, so iterating on passwords never risks the source.

Does the encrypted file get larger?

Slightly. Usually a few KB to a few dozen KB. AES encryption layers protection on top of the existing data, it does not balloon the size.

Can I encrypt multiple PDFs at once?

Not in this version — one PDF at a time. Upload, process and download each file in turn. Batch support may come later.

Can I still compress, merge or watermark after encrypting?

Do those first, then encrypt. Most processing tools refuse to read an encrypted PDF, so trying to compress or watermark after locking it is a dead end.

Does it work on mobile?

Yes — both iOS Safari and Android Chrome run it. Memory is tighter on mobile, so very large scans are smoother on a desktop browser.

What if I forget the password?

The tool keeps no record of any password you have set. Once a password is lost, that locked PDF cannot be opened again. A password manager or a memorable high-entropy passphrase is the practical safeguard.

How does it compare to SmallPDF, iLovePDF or Adobe Acrobat?

The main difference is where the work happens. This tool processes everything in your browser; those services typically upload the PDF to their servers and stream the result back. Feature-wise this tool only does encrypt and decrypt, but the sibling PDF utilities — split, merge, organize, watermark, compress — combine naturally with it.

Related tools

Encryption is one link in the distribution chain. Compressing, watermarking, merging, splitting and reordering all live in the same category.