Is the encryption cryptographically secure?

Yes. The tool uses the browser's native Web Crypto API (SubtleCrypto), which provides a specification-compliant AES-256 implementation.

Which AES modes are supported?

AES-256-CBC and AES-256-GCM are supported. GCM is recommended for new applications as it provides authenticated encryption.

Yes. All encryption and decryption happens in your browser. Nothing is sent to any server at any point.

Best Free Online AES Encryption Tool

AES-256 is the industry standard symmetric encryption algorithm, used to protect sensitive data at rest and in transit. devtoolkit.sh's AES Encryption tool lets you encrypt or decrypt any text using AES-256-CBC or AES-256-GCM directly in your browser — no data is ever sent to a server, making it genuinely private. Provide a passphrase or hex key, select the mode, and get the encrypted ciphertext or decrypted plaintext instantly. This is useful for developers testing encryption logic, generating encrypted payloads for testing, learning how AES works, and encrypting sensitive configuration values before storing them. The tool uses the Web Crypto API for cryptographically correct implementations.

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FAQ

Is the encryption cryptographically secure?: Yes. The tool uses the browser's native Web Crypto API (SubtleCrypto), which provides a specification-compliant AES-256 implementation.
Which AES modes are supported?: AES-256-CBC and AES-256-GCM are supported. GCM is recommended for new applications as it provides authenticated encryption.
Is my data safe?: Yes. All encryption and decryption happens in your browser. Nothing is sent to any server at any point.