Base64 Decoder
Decodes Base64 back to text, with or without padding, plain or URL-safe.
Results
What this tool does
Base64 turns up wherever bytes have to travel as text: the middle section of a JSON web token, the src of an inline image, the Authorization header of a basic-auth request, the body of an email attachment. Decoding it is how you see what is actually in there. The result is read back as UTF-8, so accented text comes out the way it went in rather than as a row of question marks.
Formula
every four characters go back to three bytes
Variables
| Symbol | Meaning | Unit |
|---|---|---|
text | Base64 | — |
OUT | Text | — |
SA | Size after | B |
Worked example
- Base64UGFyaXRpYW4=
- TextParitian
- Size after8 B
Limitations
- The calculation runs entirely in your browser. The values you type are never sent to a server.
Frequently asked questions
Does it accept Base64 without the padding?
Yes. The equals signs at the end only pad the last group up to four characters, and the length alone is enough to know how many bytes there were, so they can be left off. It also accepts the URL-safe variant, where the plus and slash are written as minus and underscore — that is the form used inside JSON web tokens and in query strings, and it decodes here without any change of setting.