AES Encrypt & Decrypt Online
Encrypt text with AES-256 in GCM, CBC, or CTR mode.
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.
Frequently 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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