No upload, 100% local, no account

AES Encrypt / Decrypt

Encrypt or decrypt text using AES-256-GCM. Nothing leaves your browser.

How AES Encrypt / Decrypt works

Encrypt or decrypt text snippets using AES-256-GCM through the browser's native Web Crypto API. The passphrase is stretched into a 256-bit key with PBKDF2 over a random salt, and AES-256-GCM is an authenticated mode, so any tampering with the ciphertext is detected on decryption.

Important caveats: if you forget your passphrase, the encrypted data cannot be recovered, there is no backdoor, no account, no reset mechanism. Security depends entirely on choosing a strong, unique passphrase. This tool is designed for text snippets, not large binary files.

Frequently asked questions

Are my files uploaded to a server?

No. Every operation runs inside your browser tab using JavaScript and WebAssembly. Your file is read into memory on your own device, processed there, and the result is offered as a local download. Nothing is transmitted to Sunasty or any third party. You can verify it yourself: open your browser DevTools, go to the Network tab, and watch, no request carries your file.

What happens if I lose my passphrase?

The data is permanently unrecoverable. AES-256-GCM with a key derived from your passphrase offers no backdoor. There is no account, no reset link, and no way to brute-force a strong passphrase. Keep your passphrase safe.

How is the passphrase turned into an encryption key?

The tool uses PBKDF2 (a standard key-derivation function) with a random salt and a high iteration count to derive a 256-bit AES key from your passphrase. The salt is stored alongside the ciphertext so decryption is possible with the same passphrase.

Is AES-256-GCM the same as what banks and governments use?

AES-256 is a widely adopted standard used in TLS, disk encryption, and government communications. However, the overall security of any encrypted message also depends on your passphrase strength and how you share the ciphertext, the algorithm itself is sound.

Does it work offline?

Yes, once the page has loaded. Because the processing happens on your device, you can disconnect from the network and the tool keeps working. This is the clearest proof that your data never leaves your machine.

Is it free? Do I need an account?

It is completely free and requires no sign-up. There are no watermarks, no daily limits and no tracking cookies needed to use the tool.