Decode Base64 back to readable text, with clear errors when it is not valid.
Standard Base64
A plain encoded string
SGVsbG8sIFdvcmxkIQ==URL-safe, unpadded
As found in JWTs and query strings
eyJhbGciOiJIUzI1NiJ9Encoded Unicode
Multi-byte characters decode correctly
Q2Fmw6kg4piVIOKAlCBuYcOvdmU=Standard Base64
A plain encoded string
SGVsbG8sIFdvcmxkIQ==URL-safe, unpadded
As found in JWTs and query strings
eyJhbGciOiJIUzI1NiJ9Encoded Unicode
Multi-byte characters decode correctly
Q2Fmw6kg4piVIOKAlCBuYcOvdmU=Standard or URL-safe, padded or not. Whitespace and line breaks are ignored, so a wrapped MIME block works as-is.
Decoding runs as you type. If the result should be JSON, the JSON formatter will make it readable.
Copy the decoded text, or download it when the result is long.
Hyphens and underscores are converted back automatically and missing padding is restored, so JWT segments decode without editing.
Invalid Base64 and valid Base64 that is not text are different problems, and the tool says which one you have.
Decoding happens in your browser, so pasting a session token or API response does not disclose it.
Decode any Base64 string back to the text it represents. URL-safe input is handled automatically — the alphabet is normalised and missing padding restored — so tokens copied out of a URL or a JWT decode without manual fixing. When a string is not valid Base64, or decodes to bytes that are not readable text, you are told which of those two things went wrong, because the fix is completely different in each case.
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