AES Encrypt & Decrypt Online
Encrypt text with AES-256 in GCM, CBC, or CTR mode.
Free · no sign-up · runs locally·
About this tool
AES (Advanced Encryption Standard) is the symmetric cipher standardized by NIST in 2001 and used everywhere from TLS to disk encryption. This tool derives a key from your password with PBKDF2-SHA-256 (310,000 iterations), generates a random salt and IV, and packages everything into a single portable Base64 string.
GCM is the recommended mode: it is authenticated, so tampering with the ciphertext is detected on decryption. CBC and CTR are provided for interoperability with legacy systems. All operations use the Web Crypto API — your plaintext and password never leave this page.
Like everything on encrypt.tools, this runs entirely in your browser — nothing you enter is transmitted or stored.
Do the same in a terminal
Reproduce or cross-check this tool with standard command-line utilities. For deterministic operations like hashing and encoding, the output matches exactly.
# Encrypt (prompts for a password). Note: OpenSSL's own container format,
# not interchangeable with this tool's output.
openssl enc -aes-256-cbc -pbkdf2 -iter 600000 -salt -a -in message.txt -out message.enc
# Decrypt
openssl enc -d -aes-256-cbc -pbkdf2 -iter 600000 -a -in message.encFrequently asked questions about AES Encryption
Is this AES encryption secure?+
Yes — it uses AES-256 via the browser's Web Crypto API with a key derived from your password using PBKDF2-SHA-256 (310,000 iterations), a random salt, and a random IV. GCM mode also authenticates the ciphertext so tampering is detected. Security depends on choosing a strong password.
Can I decrypt the output somewhere else?+
The output is a compact custom container (magic bytes, mode, salt, IV, ciphertext, all Base64) specific to encrypt.tools. Decrypt it with the Decrypt tab here. It is not a standard OpenSSL or GPG format.
Which mode should I choose?+
GCM — it is authenticated, so any tampering with the ciphertext is caught on decryption. Use CBC or CTR only to interoperate with a system that requires them.
Is my password sent anywhere?+
No. Key derivation and encryption happen entirely in your browser; your password and plaintext never leave your device.
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