AES Decryption Online
Decrypt AES text or files in your browser. Paste data from AES Encrypt and enter the password, or use Key + IV for AES-GCM, CBC and CTR. Nothing is uploaded.
How to use AES Decrypt
- 1Paste the encrypted Base64 or Hex text, or choose Decrypt file for a .enc file.
- 2Enter the same password, or switch to Key + IV and enter the key and IV in Hex or Base64.
- 3Press Decrypt and copy or download the original. A wrong password or changed data gives a clear error.
What makes it better
- Reads mode, key size, salt and iterations from the data in Password mode
- Key + IV mode for raw AES-GCM, CBC (PKCS#7) and CTR ciphertext
- GCM detects wrong passwords and tampering instead of returning garbage
- Decrypts files up to 100 MB and restores the original file name
- Runs locally, with no network request for your data
About AES Decrypt
AES Decryption Online reverses encryption made with this site's AES Encrypt: paste the Base64 or Hex text, enter the password, and the original comes back. The mode, key size, salt and iteration count are read from the data itself, so only the password is needed. For ciphertext produced elsewhere, Key + IV mode accepts a raw key, IV and optional GCM additional data.
Common uses
- Open a message or file you encrypted earlier with AES Encrypt.
- Check that ciphertext from your own code decrypts correctly with a given key and IV.
- Read a Base64 AES-GCM payload from a log or config when you hold the key.
- Confirm that a backup file is intact, because GCM refuses to decrypt damaged data.
Example
Input
TlNBRQEBAwAJJ8CgoaKjpKWmp6ipqqusra6vEBESExQVFhcYGRobajFkwcbBzPjTmjRnD1Cg7oeVlpEv8uRrGMqXC1qI0TE+v4/T0ExGCiPaFohjXRr3sdwjYWlpYtbfMNBa76Z5XksthtOMVeE4uXGIZaK9qsobwrq6sR7flbxRweURcAPc8tEQu+4=
Result
Meet at the north gate at 9:30. Bring the signed contract — नमस्ते 👋
Good to know
- Example: the sample encrypted text decrypts with the password example-password. A different password fails with a single, deliberately vague error.
- Ciphertext from another website or library usually has no NSAE header, so it will not decrypt in Password mode. Use Key + IV and match the mode, key size and IV exactly.
- AES-CBC and AES-CTR cannot tell a wrong key from a right one. With a wrong key you may get unreadable bytes rather than an error, and with AES-CTR a wrong key always yields random-looking data.
AES Decrypt FAQ
Can I decrypt AES without the password?
No. A strong password and AES-256 cannot be broken by any known practical method, and the password is never stored or sent anywhere, so lost passwords mean lost data. The only route is guessing the password, which takes impractically long for random ones.
Why can't I decrypt text from another website or tool?
Tools differ in how they derive the key, which IV they use and how they format the output. This page only reads its own envelope in Password mode. For other tools, use Key + IV and enter the exact key, IV, mode and encoding they used.
Why does it say the password is wrong or the data was changed?
With AES-GCM the authentication tag fails to verify in both cases, and the two cannot be told apart. Check for typos, an extra space, copied line breaks or a truncated string. We show one message so nothing about the data is leaked.
What IV and key format does Key + IV mode expect?
Keys are 16, 24 or 32 bytes for 128, 192 or 256-bit AES, and the IV is 12 bytes for GCM or 16 bytes for CBC and CTR, each written as Hex or Base64. The ciphertext should be only the encrypted bytes, with the GCM tag at the end.