Base64 Encoder & Decoder

Convert text to Base64 or decode it back to UTF-8, with standard and URL-safe alphabets and clear validation errors.

Text stays in this page’s memory and is omitted from share links. Reloading clears it. Limit: 100,000 UTF-16 units.

0 UTF-16 units in the output.

Base64 is reversible encoding, not encryption. Input text uses UTF-8; decoding accepts optional padding and ASCII whitespace, and rejects invalid UTF-8 or noncanonical trailing bits.

Encoding Unicode text

The encoder turns your text into UTF-8 bytes, then represents those bytes with Base64 characters. Standard output uses the + and / characters and final = padding when needed. URL-safe output uses - and _ instead and omits padding.

For example, Hello becomes SGVsbG8=. The emoji 😀 becomes 8J+YgA==. Choose the alphabet expected by the system receiving your text.

Decoding and validation

This decoder accepts padded or unpadded input and ignores ASCII spaces, tabs and line breaks. It rejects characters outside the chosen alphabet, misplaced padding and nonzero unused trailing bits.

The output must be valid UTF-8 text. Encoded images, archives and other binary files may not decode as text. A decoding error does not necessarily mean a binary file is corrupt; it may be outside this tool’s text-only scope.

Copy, reverse and privacy

Use Copy result to copy only the output. Reverse conversion places the result in the input and changes direction. It is unavailable if the output exceeds the input limit of 100,000 UTF-16 units.

Input is held in page memory and is not placed in a URL or local storage. Share links omit it, and reloading clears it. Base64 does not conceal information: anyone with the encoded text can decode it.

References

Frequently asked questions

Is Base64 encryption?

No. It is a reversible representation of bytes without an encryption key.

Can I decode a binary file here?

This tool is for UTF-8 text. Bytes that do not form valid UTF-8 produce an error rather than replacement characters.

Why are standard and URL-safe results different?

They use different characters for two alphabet entries. This encoder also omits padding in URL-safe mode.

Last updated . Results are estimates for informational purposes only.