AES Encryption & Decryption Online — 128 / 192 / 256, GCM & CBC

No. The entire encryption/decryption runs in your browser via the Web Crypto API (SubtleCrypto). You can verify with your browser's DevTools Network panel — nothing is sent to any server. That's what makes it safe to use with real passphrases and real data.

AES-GCM is the modern default — it's an authenticated cipher, meaning decryption also verifies the ciphertext wasn't tampered with, and fails loudly if it was. Use AES-CBC only when you need to inter-operate with legacy systems that don't support GCM. Never use CBC without a separate MAC in production systems.

Through PBKDF2 with SHA-256 and 200,000 iterations, salted with 16 random bytes per encryption. The salt is included in the ciphertext header, so decryption doesn't need it stored separately. 200k iterations balances speed with brute-force resistance for typical passwords.

No. This tool produces a self-describing format (magic prefix + mode + key size + iteration count + salt + IV + ciphertext, all base64-encoded) so it can decrypt its own output without asking for parameters. It does not follow openssl's format or CryptoJS's format. If you need cross-tool interop, encrypt with the target system and paste it there.

No — it's a primitive, not a protocol. Real systems combine AES with a proper key management story (KMS / HSM), authenticated framing (AES-GCM alone doesn't defend against replay), and often authenticated encryption libraries like libsodium's secretbox. Use this tool for ad-hoc encryption, learning, or verifying your production ciphertext round-trips correctly.