AES-CTR Encrypt & Decrypt
AES encryption in CTR (stream) mode with a random counter/IV. This tool does both encrypt and decrypt on one page — pick a mode, paste your data, and click. Everything runs on your device, nothing is sent to a server.
The key is derived from this password via PBKDF2 (200k iterations). Must match to decrypt.
Everything runs in your browser. Your data is never sent to our servers.
Example
Example Input
Secret message
Example Output
q2Rn…(Base64 ciphertext)
How to Use
- 1Choose Encrypt or Decrypt mode at the top.
- 2Fill the Input field and, if required, complete the fields in "More settings" (key/password).
- 3Click the button (or press Ctrl+Enter) to process.
- 4Copy the result with the Copy button.
About AES-CTR
AES-CTR (Counter) turns AES into a stream cipher: it encrypts an incrementing counter value, then XORs the result with the plaintext. This allows parallel encryption and random access.
This tool derives the key from a password (PBKDF2) and uses a random counter/IV block prepended to the ciphertext (Base64). Like CBC, CTR is not authenticated.
CTR is useful when you need stream-cipher behavior. For end-to-end security with integrity, choose AES-GCM, which is essentially CTR + authentication.
FAQ
Are my data or keys sent to a server?
No. AES-CTR runs entirely in your browser using the Web Crypto API and client-side libraries. Your data, passwords, and keys never leave your device.