How to Decrypt AES-256 Text Online with a Password

To decrypt AES-256 text, paste the Base64 blob into the ByteTools AES Text Decrypter, enter the exact password used to encrypt it, and click Decrypt — the tool recovers the original message right in your browser. The salt and initialisation vector are already embedded in the blob, so there is nothing else to supply. This guide walks through the process step by step and explains what happens under the hood.

What you need before you start

Decryption requires just two things: the Base64 blob produced by an AES encrypter, and the password used at encryption time. There is no separate key file, salt or IV to track — all of those are packed inside the blob itself. If you are missing the password, the message cannot be recovered, because AES-256 is designed to make guessing infeasible.

Step-by-step decryption

1. Paste the Base64 blob. Drop in the string produced by the AES Encrypt Text tool. It contains the salt, the IV and the ciphertext together.
2. Enter the password. Type the exact password used to encrypt the text — capitalisation and every character must match.
3. Click Decrypt. The tool reads the embedded salt, re-derives the AES-256 key with PBKDF2, and decrypts the ciphertext with AES-GCM.
4. Read the result. The recovered plain text appears in the result box, ready to copy.
5. Fix a wrong password if needed. If the password is incorrect or the blob was altered, the tool reports it clearly instead of showing garbled text.

What happens under the hood

Understanding the flow helps you troubleshoot. Here is what each part of the blob does during decryption:

Component	Role in decryption
Salt	Feeds PBKDF2 so the same password re-derives the same 256-bit key
IV	Initialises AES-GCM so the ciphertext decrypts correctly
Ciphertext	The encrypted message, turned back into plain text
Auth tag	Verifies integrity; a mismatch triggers the wrong-password message

Because AES-GCM is authenticated, a wrong password does not produce nonsense output — the tag check fails and the tool tells you plainly, so you never trust corrupted text by mistake.

Why it is safe to do here

Decryption runs entirely in your browser using the standard Web Crypto API. Your ciphertext and password are never uploaded, stored or logged, and the tool works offline. That means recovering a sensitive message — a stored credential, a private note, a shared secret — stays confined to your own device.

Try the AES Text Decrypter — free and 100% in your browser.

FAQ

Which blobs can this tool decrypt?

It decrypts blobs created by the matching ByteTools AES Encrypt Text tool, which use the format salt, then IV, then AES-GCM ciphertext, all Base64-encoded together. Blobs from other tools may use a different layout and will not decrypt here.

What if I only have part of the blob?

The whole blob is required. Since the salt and IV sit at the start and the auth tag protects the ciphertext, a truncated or edited blob fails the integrity check and cannot be decrypted. Paste the complete, unmodified string.

Do I need an internet connection?

No. Once the tool has loaded, decryption happens locally, so you can recover messages while completely offline — useful when handling secrets on an air-gapped machine.

Can the tool recover the password for me?

No. There is no backdoor or reset. Strong AES-256 encryption is specifically built so plaintext cannot be recovered without the password, which is what makes it trustworthy for real secrets.

Related free tools

• AES Text Encrypter — create the blobs this tool decrypts.
• HMAC Generator — produce keyed message authentication codes.
• SHA-256 Hash Generator — hash data for integrity checks.
• Hash Comparer — compare two hashes safely.

Built by ByteVancer

ByteTools is a free product of ByteVancer, a software and web development studio building web apps, SaaS and custom software. If you need secure, well-built software for your team, explore what ByteVancer can create for you.