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Base64 Decoder
Decode Base64 back to text, including JWT payloads.
Quick Tool Overview
The Base64 Decoder turns Base64 back into readable text, forgiving the things that usually break a decoder: missing padding, the URL-safe alphabet, line breaks and whitespace. JSON results are pretty-printed, which is what you want when the input was a JWT payload.
- What it does
- Decodes Base64 into readable text
- You give it
- A Base64 string from a token, header or log
- You get back
- The decoded text, with JSON formatted
- Best for
- Inspecting JWTs, data URIs and encoded headers
About the Base64 Decoder
Base64 arrives from all sorts of places and rarely in a clean form. A JWT segment has no padding and uses the URL-safe alphabet. A value copied from a log has line breaks through it. A header value is percent-encoded on top of the Base64.
This decoder handles all of that. Padding is restored if it is missing, both alphabets are accepted, whitespace is stripped, and the decoded bytes are read as UTF-8 so non-English text comes back correctly. If the result is JSON it is pretty-printed, which is what you almost always want when the input was a JWT payload. Nothing is uploaded, which matters because tokens routinely contain personal data.
Key features of the Base64 Decoder
Padding restored automatically
JWT segments drop their trailing = characters, so the decoder adds them back rather than failing.
Both alphabets accepted
Standard and URL-safe Base64 decode without you having to say which it is.
JSON pretty-printed
A decoded token payload comes back readable instead of as one long line.
Correct UTF-8 decoding
Non-English text comes back intact rather than as a run of replacement characters.
Nothing is uploaded
Tokens routinely carry personal data, so the decode happens entirely in your browser.
How to use the Base64 Decoder
-
1
Paste the Base64
From a token, a header, a data URI or a log — padding and line breaks are handled.
-
2
Read the decoded text
UTF-8 is decoded properly, so non-English text comes back intact.
-
3
Check the JSON view
If the result is JSON, it is pretty-printed automatically.
-
4
Copy what you need
Nothing is uploaded, so decoding a token here does not expose it.
Frequently asked questions
Yes, for the header and payload segments — split the token on its full stops and paste either of the first two parts. The signature is binary and will not decode to readable text, which is expected.
It is restored automatically. JWTs and many URL-safe Base64 values drop the trailing = characters, so the decoder adds them back before decoding rather than failing.
Usually because the data was not text to begin with — an image or a compressed file will decode to bytes that are not readable characters. That is the data being correct rather than the decoder failing.
The decoding happens entirely in your browser and nothing is transmitted or stored. That said, a token that has been pasted anywhere should be treated as needing rotation.
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