No, and it is not intended to be. It is a way of writing bytes using 64 printable characters so they survive a text-only channel. Anyone can reverse it without a key. If a value needs to be secret, it needs encryption.

Why does my string end in one or two equals signs?

That is padding. Base64 works in groups of three bytes, and when the last group is short the encoder pads the output so the length stays a multiple of four. One = means the final group had two bytes; two means it had one.

What is URL-safe Base64?

A variant that swaps + for - and / for _, because the standard characters have meanings inside a URL. JWTs use it. This decoder accepts both without you converting anything.

Can I decode a Base64 image here?

It will decode, but the result is raw image bytes shown as text, which is not useful. For a data URI, paste it into your browser's address bar instead — the browser will render it.

Base64 Decoder

Decodes Base64 back to text, and tells you when the input is not valid Base64 rather than returning something that merely looks like an answer.

Runs in your browser — nothing is uploaded

Input

Output

Your result appears here. Everything runs in your browser.

Need this as an API?

Why use it

Built to be genuinely useful

Handles URL-safe Base64

JWTs and query parameters use - and _ in place of + and /. Those decode here without you having to substitute them by hand first.

Says when it cannot decode

A string with the wrong length or an illegal character is reported as invalid. Silently discarding the bad bytes is how a decoder returns plausible nonsense.

Nothing is uploaded

It runs in your browser. Tokens, keys and customer data routinely end up in these tools, and none of it should have to cross a network to be decoded.

Free, no sign-up

No account, no daily cap, and no feature held back behind a paywall.

How it works

Three steps

1
Paste the Base64 string.
2
Read the decoded text, or the reason it could not be decoded.
3
Copy the result out.

Base64 is not encryption

It is worth being blunt about this, because it is the single most common misunderstanding about Base64 and it has consequences. Base64 is an encoding, not a cipher. There is no key, nothing is secret, and anybody who can see the string can read it in about a second — which is exactly what this page does.

That matters when a password, an API key or a customer record has been Base64'd and treated as protected. It is not protected. It is written in a different alphabet. If the value would be a problem in plain text, it is a problem in Base64 too, and the fix is encryption or not transmitting it at all.

What Base64 is genuinely for is moving binary through a channel that only tolerates text: an email attachment, a JSON string, a data URI in a stylesheet. It costs about a third more bytes than the original in exchange for surviving that trip intact.

Why a decode sometimes produces gibberish

If the original data was not text, the decoded bytes will not be text either. A Base64 string of a PNG decodes to PNG bytes, and rendering those as characters gives you a screen of symbols. That is the decoder working correctly on input that was never text to begin with.

The other cause is a truncated string. Base64 encodes three bytes into four characters, so the length of a complete string is always a multiple of four, padded with = if needed. A string that has lost its tail decodes up to the break and then has nothing coherent left, which is why the end of the output turns to noise while the beginning reads fine.

FAQ

Questions people ask

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