It says it would not decrypt. What went wrong?

One of two things: the password does not match, or the block is not byte-for-byte what was produced. A missing final line, an autocorrected character, or a chat client that reflowed the text will all cause it. Copy the original again and retry before assuming the password is wrong.

Why does changing the rounds setting have no effect?

Because the real value is stored inside the message and takes precedence. The control is there so the panel matches its counterpart on the encrypt page; the figures shown with your result are the ones actually used.

Can this open files encrypted by other tools?

No. It expects the container this site writes, which begins with a specific marker. Output from OpenSSL, GPG, 7-Zip or another web tool uses a different layout and will be refused rather than misread.

Does the decrypted text get stored anywhere?

It exists in the memory of this tab and nowhere else. Close the page and it is gone. Nothing is written to disk, to storage, or to any server, because there is no server involved at any point.

Decrypt Text

Open text encrypted here, with the password it was sealed with.

Everything runs inside your browser. Your files never leave your device.

Input

Result

The result appears here as you type.

Ask about Decrypt Text

Questions about what this tool does, which option to pick, or what it can and cannot handle.

The question you type here is sent to an AI provider to be answered — your files and whatever you put in the tool above are not, and the assistant cannot see them. Answers are generated and can be wrong. The tool itself is not guessing: it runs deterministic code on your device.

About the Decrypt Text

This opens text that was sealed with the encrypt tool on this site. Paste the block, supply the password it was sealed with, and the original words come back.

The settings shown in the options panel are deliberately not used. Every encrypted block produced here carries its own parameters inside it — how many PBKDF2 rounds derived the key, which hash was used, the random salt, the initialisation vector — and those are read out of the message and used in preference to anything selected on screen. That design decision has a practical consequence worth stating plainly: a block encrypted three years ago, when the defaults on this page were different, still opens today without anyone having to remember what those defaults were. Formats that leave the parameters implicit are the reason old encrypted archives become unopenable.

If decryption fails, the message says the password is wrong or the data has been altered, and it deliberately does not guess which. AES-GCM verifies the whole message against an authentication tag before it will hand back a single byte, and a failed tag has exactly two causes: a key that does not match, or content that changed after it was sealed. The cipher genuinely cannot distinguish them, and a tool that claimed to would be inventing the answer.

That failure mode is a feature rather than an inconvenience. It means a partially corrupted download refuses to open rather than returning plausible-looking nonsense, and it means an attacker who alters the ciphertext in transit cannot make it decrypt into something else of their choosing. You either get exactly what was sealed, or you get told that you cannot.

How to use it

1Paste the whole encrypted block into the input, including every line if it was wrapped.
2Enter the password it was sealed with.
3The recovered text appears below. The figures above it report the settings that were read out of the message itself.
4If it refuses, check the password first and the completeness of the pasted block second — a truncated copy fails in exactly the same way as a wrong password.

Questions

It says it would not decrypt. What went wrong?: One of two things: the password does not match, or the block is not byte-for-byte what was produced. A missing final line, an autocorrected character, or a chat client that reflowed the text will all cause it. Copy the original again and retry before assuming the password is wrong.
Why does changing the rounds setting have no effect?: Because the real value is stored inside the message and takes precedence. The control is there so the panel matches its counterpart on the encrypt page; the figures shown with your result are the ones actually used.
Can this open files encrypted by other tools?: No. It expects the container this site writes, which begins with a specific marker. Output from OpenSSL, GPG, 7-Zip or another web tool uses a different layout and will be refused rather than misread.
Does the decrypted text get stored anywhere?: It exists in the memory of this tab and nowhere else. Close the page and it is gone. Nothing is written to disk, to storage, or to any server, because there is no server involved at any point.