Base64 Decode
Decode a Base64 string back to text.
How to use the Base64 Decode
- Paste your Base64 string.
- Copy the decoded text.
About the Base64 Decode
Paste a Base64 string and get the original text back. Decoding needs no key and no permission, which is the honest headline: Base64 is an encoding, not encryption. If you have found a Base64 blob in a config file or an HTTP header and assumed it was protected, it is not — this page settles that in one paste.
It expects the standard alphabet: A–Z, a–z, 0–9, +, / and = padding. URL-safe Base64, which substitutes - and _ for + and /, is rejected as invalid here — swap those two characters back first, or reach for the JWT decoder if you are working on a token, since it expects that variant. Surrounding whitespace is trimmed, and anything the decoder cannot make sense of returns a clear error rather than quiet garbage.
The decoded bytes are then interpreted as UTF-8, which covers virtually all real-world text. If the underlying bytes are not text at all — an encoded image, say — you will see replacement characters rather than an error, because the Base64 itself decoded perfectly well; the bytes simply are not readable text. Going the other direction, use the Base64 encoder. Both run entirely in your browser.
Frequently asked questions
Why does it say my input is invalid?
Usually one of three things: the string contains characters outside the standard alphabet, it is URL-safe Base64 using - and _, or it has been truncated so the length is not decodable. Check for stray quotes or a copied-off ending.
Can I decode a JWT here?
Only awkwardly. JWT segments use Base64URL, so you would have to replace - with + and _ with /, add back any padding, and decode each dot-separated part on its own. The JWT decoder does all of that for you and pretty-prints the header and payload.
Why do I get question marks or odd symbols in the output?
The Base64 decoded fine, but the resulting bytes are not valid UTF-8 text — you are probably looking at an encoded image, archive or other binary. Those bytes have no textual meaning, so the replacement character appears instead.
Is decoding Base64 the same as decrypting it?
No. There is nothing to decrypt. Base64 is a public, reversible transformation with no key, so decoding is just reading. Anything sensitive found in a Base64 string was never protected in the first place.
Is my input sent to a server?
No. Decoding happens in your browser using its built-in decoder, so you can paste tokens or payloads without them leaving your machine.