🔓 Base64 Decoder

Paste Base64 and get the original text back. URL-safe Base64, missing padding and stray whitespace are all handled automatically. Decoding happens in your browser — nothing is uploaded.

Base64 to decode

Decoded live as you type. Line breaks and spaces are ignored.

What happens to the string you paste

Base64 packs three bytes into four characters, six bits each. Decoding reverses that, and this page cleans the input first: whitespace and line breaks are removed, the URL-safe characters - and _ become + and /, and missing = padding is added back before decoding.

SGVsbG8sIHdvcmxkIQ==  ->  13 bytes  ->  "Hello, world!"
Y2Fmw6k=              ->   5 bytes  ->  "cafe" with an accented e (4 characters)

Those two counters are the stat tiles above. They differ whenever the text is not plain ASCII, because an accented or emoji character costs two to four bytes in UTF-8.

When it will not decode

Stray characters. Anything outside A-Z a-z 0-9 + / = after the URL-safe swap is rejected. The usual culprits are a leading data:image/png;base64, prefix or quotation marks copied with the value.
It decoded, but it is not text. Bytes are checked against strict UTF-8; if they fail, you get a byte count and a hex dump of the first 256 bytes instead, which is normally an image or archive rather than a broken string.

Decoding runs in your browser through the built-in atob and TextDecoder, so nothing you paste is uploaded. Copy and Download .txt are offered only for results that came out as text.

Frequently asked questions

What do the equals signs at the end mean?

They pad the last group to four characters. One = means the final group held two bytes, two = means it held one. The decoder here re-adds them if they were stripped, so an unpadded string still works.

Why does my Base64 fail to decode?

Almost always something extra was copied with it - a URL prefix, a trailing comma, or a truncated value whose length is not a multiple of four once padded. The error message tells you which of the two it is: an invalid character, or bad length.

Is Base64 a form of encryption?

No. It is a reversible transport encoding with no key, designed to move bytes through text-only channels such as email or JSON. A Base64 password is readable by anyone who pastes it into this page.