Encrypt any file, right in your browser. Free, open source, and fully client-side. Nothing is ever uploaded.

Try it live → · VERNAM.app →

⭐️ We just launched, and a single star genuinely helps. VERNAM is free and open source, with nothing to sell and no one funding it. If you think strong encryption should be free for everyone, please star us on GitHub. It helps more people find the project and keeps it alive.

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VERNAM is a tiny, drag-and-drop file encryptor that runs entirely in the browser. Drop a file, set a passphrase, done. Drop the encrypted file back in, type the passphrase, get your original. That is the whole product.

It is named after Gilbert Vernam, inventor of the one-time pad, the only cipher ever mathematically proven unbreakable. VERNAM (the tool) is not a literal one-time pad, but it is built on its descendant: XChaCha20, a modern stream cipher.

Made by PrivacyTools.io.

Why it is different

• Nothing leaves your device. No uploads, no cloud, no servers. Go offline and it still works.
• No account, ever. No sign-up, no email, no tracking.
• Any file, any size. Large files stream straight to disk instead of eating your memory.
• Tamper-evident. Change one byte and decryption fails loudly.
• Open source. Audit it, fork it, host it yourself.

Cryptography

• Key derivation: Argon2id stretches your passphrase into a 256-bit key.
• Encryption: XChaCha20-Poly1305 via libsodium's secretstream (authenticated, streaming).
• Integrity: per-chunk authentication plus truncation and reordering detection.

These are the same peer-reviewed primitives behind Signal, WireGuard, and 1Password. The container format is documented in FORMAT.md.

One honest warning: there is no backdoor and no recovery. If you forget the passphrase, the file is gone. That is the point. Use the built-in generator and store it somewhere safe.

Please host your own copy

We want this everywhere. The more places strong, free encryption lives, the harder it is to take away. Put VERNAM on your own domain, your blog, your company intranet, a USB stick, anywhere. There is no build step and no dependencies to install, it is a handful of static files.

Run it locally:

git clone https://github.com/LifetimeLabsDev/VERNAM.git
cd VERNAM
python3 -m http.server 8000
# open http://localhost:8000

(Any static file server works. Opening index.html as a file:// will not, because browsers block WebAssembly and the File System Access API on the file: scheme.)

Put it on the web: drop the folder on any static host (your own nginx, GitHub Pages, Netlify, Cloudflare Pages). No backend, no config. That is exactly how VERNAM.app runs.

Streaming-to-disk for large files uses the File System Access API (Chromium-based browsers). Firefox and Safari fall back to an in-memory download, capped at 2 GiB.

The one condition: link back to PrivacyTools.io

VERNAM is released under the VERNAM License (a custom, WTFPL-style license, not OSI-approved). Do almost anything you like with it, copy it, change it, sell it, ship it, on one condition: keep a clear, visible, working link back to PrivacyTools.io on any hosted or distributed copy.

Concretely, if you run VERNAM as a website or app, put a real, clickable link to https://www.privacytools.io somewhere ordinary visitors can see it. A footer line is plenty, for example:

Powered by VERNAM, from PrivacyTools.io.

Make the link work, and do not imply that PrivacyTools.io endorses your version. That is the entire ask. We would rather you spread this far and wide than lock it down, the link is how we keep the lights on. The exact terms (including the patent grant and the names/trademark note) are in LICENSE.

VERNAM also bundles a few permissive third-party components (libsodium under the ISC License, the BIP-0039 wordlist under the MIT License); keep their notices in THIRD-PARTY-LICENSES.txt when you redistribute. The crypto primitives themselves (XChaCha20-Poly1305, Argon2id, BLAKE2) are open, unpatented standards.

Brand assets

Writing about VERNAM, or adding that credit link? Grab the logo, the cipher-grid mark, and the color palette from the PrivacyTools.io brand kit instead of recreating them by hand:

https://www.privacytools.io/brand#vernam

What is in here

File	What it is
index.html	The page: hero, the tool card, and the marketing sections.
assets/css/card.css	Styles for the tool card.
assets/js/vernam-ui.js	Wiring for the tool card (drives the engine).
assets/js/vernam.js	The crypto engine. Exposes window.Vernam.
assets/js/wordlist.js	BIP-0039 English wordlist for the passphrase generator.
assets/vendor/sodium.js	Vendored libsodium (ISC). No CDN, works offline.
FORMAT.md	The .vrn file format spec.
LICENSE	The VERNAM License (see above).
THIRD-PARTY-LICENSES.txt	Notices for the bundled components.

The tool card (index.html's card markup, assets/css/card.css, assets/js/vernam-ui.js) and the engine (assets/js/vernam.js) are generated from the canonical PrivacyTools.io source, so this copy always matches the live tool at privacytools.io/encrypt.

Using the engine on its own

<script src="assets/vendor/sodium.js"></script>
<script src="assets/js/wordlist.js"></script>
<script src="assets/js/vernam.js"></script>
<script>
  await Vernam.ready();
  // encryptFile / decryptFile take a File and a passphrase
  const result = await Vernam.encryptFile(file, "correct horse battery staple", {
    profile: "standard",            // or "high"
    onStage:    s => console.log(s),
    onProgress: f => console.log(Math.round(f * 100) + "%"),
  });
  // Vernam.detect(file) -> "encrypt" | "decrypt"
  // Vernam.generatePassphrase(6), Vernam.strength(str)
</script>

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Made with care by PrivacyTools.io · fighting surveillance since 2015