Base64 Decoder
Paste a Base64 string and get the original text back. Whitespace, missing padding and the URL-safe alphabet are all handled without extra settings.
How to use the Base64 Decoder
- Paste the Base64 string. Line breaks and spaces are stripped automatically.
- Press Decode. URL-safe characters and missing padding are corrected for you.
- Copy the text, or download it as a file if the content turns out to be binary.
Why decoding sometimes produces gibberish
Base64 carries no information about what the bytes mean. If the original data was a PNG, a ZIP or a protobuf message, decoding it produces exactly those bytes — which look like noise when displayed as text.
This tool detects that case. If the bytes are not valid UTF-8, it tells you so and offers a download instead of printing control characters into the page. A quick way to identify what you have: PNG files start with iVBOR in Base64, JPEGs with /9j/, PDFs with JVBER and ZIPs with UEsD.
Decoding JWTs
A JSON Web Token is three URL-safe Base64 segments joined by dots: header, payload and signature. Paste a single segment here — not the whole token — and you will get readable JSON back.
Two cautions. The signature segment is raw binary, so it will not decode to text. And decoding a payload proves nothing about the token's validity: anyone can read a JWT, and the signature is what makes it trustworthy. Never treat a decoded payload as verified.
Frequently asked questions
Why does it say the length is wrong?
Valid Base64 has a length that is a multiple of four once padding is added. If it is not, characters were lost — usually by a line-length limit in a chat client or a truncated copy.
Do I need to strip line breaks first?
No. All whitespace is removed before decoding, so you can paste MIME-wrapped output directly.
Does it detect URL-safe input automatically?
Yes. If the string contains a hyphen or underscore, those are converted to the standard alphabet and any missing padding is restored before decoding.
Can I decode a password hash with this?
No. Base64 is reversible encoding; a hash is a one-way function. If a value decodes to random bytes rather than text, it was probably a hash and cannot be reversed.
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