Base64 Decoder

Decode Base64 strings back to plain text instantly. Handles standard Base64, data URIs, JWT tokens, and MIME-encoded content.

Use this free online base64 decoder to decode any base64-encoded string back to its original text. This base64 to text converter handles standard Base64, data URIs, JWT tokens, and email MIME encoding. Decoding happens entirely in your browser for complete privacy.

Base64 Input0 characters

Decoded Text

Common Base64 Patterns

Recognize common Base64-encoded formats to quickly identify what you are decoding.

Pattern	Description	Example
Data URI	Starts with data:...	data:text/plain;base64,SGVsbG8=
JWT Token	Three dot-separated parts: header.payload.signature	eyJhbGci...eyJzdWIi...SflKxwRJ...
MIME / Email	Content-Transfer-Encoding: base64	Q29udGVudC1UeXBl...
Plain Base64	A-Z, a-z, 0-9, +, / with optional = padding	SGVsbG8gV29ybGQh

Troubleshooting Invalid Base64

Check padding: string length should be divisible by 4
Only A-Z, a-z, 0-9, +, /, = are valid characters
Remove extra whitespace and newlines
For URL-safe Base64, replace - with + and _ with /

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FAQ

How do I decode a Base64 string?

Paste your Base64-encoded string into the input field and click Decode. The tool will convert it back to readable text. It handles standard Base64 encoding as well as URL-safe variants. All decoding happens in your browser, ensuring data privacy.

What if my Base64 string is invalid?

Invalid Base64 strings will show an error message. Common issues include: incorrect padding (Base64 strings should have length divisible by 4), invalid characters (only A-Z, a-z, 0-9, +, /, and = are allowed), or truncated strings. Try trimming whitespace or fixing padding with = characters.

How is Base64 used in URLs?

Standard Base64 uses + and / characters which are not URL-safe. URL-safe Base64 replaces + with -, / with _, and removes = padding. This is commonly used in JWT tokens, URL parameters, and file names. This decoder handles both standard and URL-safe Base64.

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