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Text Encryption — AES-256, Free, Works Offline

Encrypt and decrypt text with a passphrase using AES-256-GCM, the same encryption standard used in banking and security software. Everything runs locally in your browser using the Web Crypto API — your text and passphrase are never sent to any server.

About this tool

This tool encrypts and decrypts text using AES-256-GCM, an authenticated encryption algorithm that protects both the confidentiality and integrity of the message. The key is derived from your passphrase using PBKDF2 with SHA-256 and 150,000 iterations, with a fresh random salt and IV for each encryption. The encrypted output is self-contained base64 text that can be decrypted on any device using this tool. Everything runs locally in your browser via the Web Crypto API.

How to use

  1. Enter the text you want to protect and choose a strong passphrase.
  2. Click Encrypt — copy the encrypted output to store or send it.
  3. To decrypt, switch to the Decrypt tab, paste the encrypted text, enter the same passphrase, and click Decrypt.
  4. Always share the passphrase through a different channel than the encrypted text.

When to use this tool

  • Encrypting a sensitive note, password, or private message before storing it in a cloud service or email.
  • Sending encrypted text to someone who knows the shared passphrase, through a channel that may not be secure.
  • Protecting a personal record that you want to be unreadable without the key.

Frequently asked questions

What encryption algorithm does this use?

AES-256-GCM with a PBKDF2-derived key (SHA-256, 150,000 iterations, random salt). This is a well-established standard with no known practical attacks.

Is my text or password sent to a server?

No. Everything runs in your browser using the Web Crypto API. Nothing is ever transmitted or stored.

Does this work offline?

Yes. Once the page has loaded, all encryption and decryption runs locally with no internet connection required.

How strong is this encryption?

AES-256-GCM is very strong. The security depends on your passphrase — a weak passphrase is the most common point of failure.

What happens if I forget my passphrase?

There is no recovery option. Keep the passphrase somewhere safe.

Can I decrypt on another device?

Yes. The encrypted output is self-contained base64 text. Decrypt it using this tool on any device with the correct passphrase.

How should I share the passphrase?

Always through a different channel than the encrypted text — for example, send the encrypted text by email and the passphrase by phone.

Is this tool free?

Yes, completely free with no sign-up required and no usage limits.

Encryption happens entirely in your browser (AES-256-GCM) — neither the text nor the password is ever sent to a server. Share the passphrase through a different channel than the encrypted message.