About AES Encrypt
AES Encrypt turns text into an encrypted, Base64-encoded string using AES in GCM mode with a 256-bit key. You supply a password, a fresh random 96-bit initialisation vector is generated for every run, and the IV is written in front of the ciphertext so the matching decryption step can recover it. The whole operation runs in your browser through the Web Crypto API — the plaintext and the password never leave the page.
GCM is an authenticated mode, so the output carries a tag that lets decryption detect tampering: if a byte of the ciphertext is altered, or the password is wrong, decryption fails rather than returning corrupted plaintext. That property is why GCM is preferred over older modes for new work.
One limitation is worth stating plainly: the password becomes a key through a single SHA-256 hash, with no salt and no iteration count, so the derivation is fast. That is fine for casually protecting a snippet of text, but it is weaker than PBKDF2 or Argon2 against someone who captures the ciphertext and can guess passwords offline. For valuable secrets, use a long, unique passphrase. Because the IV is random, encrypting the same text twice yields two different strings, and you must decrypt with exactly the same password.
How to use AES Encrypt
- 1 Type the password you will use to protect the text; you will need the identical value later to decrypt.
- 2 Enter the plaintext you want to encrypt in the Text field.
- 3 Copy the Base64 output, which contains the random IV followed by the ciphertext.
- 4 To reverse it, open the AES Decrypt tool, paste the Base64 string and enter the same password.
Frequently asked questions
Why is the output different every time I encrypt the same text?
Because a fresh random initialisation vector is generated on each run and prepended to the ciphertext. That is intentional — reusing an IV under the same key weakens GCM, so each encryption is unique even for identical input.
What happens if I lose the password?
The text cannot be recovered. AES has no backdoor or reset; the key is derived from the password and nothing else, and this tool keeps no copy. There is no way to decrypt without the exact password.
Is this strong enough for real secrets?
The cipher is strong, but the key derivation here is a single SHA-256 of your password with no salt or stretching. It resists a casual attacker, yet a weak, guessable password can be brute-forced offline. Use a long passphrase, and for high-value data prefer a tool that applies PBKDF2 with a high iteration count.
What does the Base64 string actually contain?
The first 12 bytes are the random IV, and the remainder is the AES-GCM ciphertext together with its authentication tag. The encryption and decryption tools agree on that layout, so you can round-trip without any extra settings.
Free, online, and private
Free to use
AES Encrypt is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How AES Encrypt behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Cipher and mode | AES-GCM, 128-bit tag, key imported from a raw SHA-256 digest of the password |
| IV | 12 random bytes from crypto.getRandomValues, drawn fresh on every run |
| Output encoding | base64 of the 12-byte IV concatenated with the ciphertext and tag |
| Same input twice | two different strings, because the IV changes each time |
| Empty input | allowed — empty text still yields 28 bytes: the 12-byte IV plus the 16-byte tag |
| Default values | password my-secret, text "Hello world" |
Compiled from the implementation of this tool and checked against it by itoolnet.
What AES Encrypt does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- A fresh random IV is drawn every run, so encrypting the same text with the same password twice gives two different base64 strings. That is correct for GCM, but it means the output cannot be used as a stable fingerprint of the plaintext or compared between runs.
- The password is stretched with a single SHA-256 pass and no salt. A short or common password therefore produces a ciphertext only as strong as the password, and two people who choose the same password derive byte-identical keys.
- The output carries no metadata. Nothing in the base64 records that the algorithm is AES-GCM, that the first 12 bytes are the IV, or which password was used, so the recipient must be told all of that separately and must use the matching AES Decrypt page.
Tested and documented by itoolnet, the team that builds and maintains this site.