Base64 Decoder

Decode Base64 back to text or a file.

Free Base64 decoder. Paste Base64 to decode it as UTF-8 text or download it as a file, with friendly errors for invalid input, all in your browser.

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About Base64 Decoder

Base64 looks like random gibberish, a long string of letters, numbers, plus signs and slashes, but it's just binary data dressed up as plain text. Email attachments, embedded images, API tokens, and cryptographic keys all travel this way, because plenty of systems only reliably handle text. Decoding reverses the disguise.

Paste any Base64 string and this tool decodes it as UTF-8 text, or downloads it as a file when the contents aren't text at all, images, PDFs, archives, and other binary payloads decode fine, they just can't be displayed as characters. If the output looks like mojibake, that's your signal to use the download option instead of squinting at it.

Everything happens in your browser; nothing you paste is uploaded anywhere. One honest limitation: if your string uses the URL-safe variant (dashes and underscores instead of plus and slash), swap those characters first, since this decoder expects standard Base64. Whitespace and line breaks, common in pasted email content, are ignored automatically.

How to use Base64 Decoder

  1. Paste your Base64 string into the input box.
  2. Click Decode as text, or Download as file for binary data.
  3. Copy the text or save the file with your chosen filename.

Why use this tool?

  • Clear error messages for invalid Base64
  • Binary-safe: download anything that is not text

Tips for best results

  • If the decoded text looks like garbage, it's probably binary data, use 'Download as file' instead.
  • URL-safe Base64 uses - and _ instead of + and /: convert those characters before decoding.
  • Line breaks and spaces in pasted Base64 are harmless here; they're ignored automatically.
  • A valid Base64 string's length is always a multiple of 4, trailing = signs are padding, not errors.
  • Decoded output is about 3/4 the size of the input; if it's wildly different, the input may be truncated.

Frequently asked questions

Is my data uploaded anywhere?
No. Decoding happens entirely in your browser.
It decoded but the text looks wrong. Why?
The Base64 may hold binary data rather than text. Use Download as file instead.
Can I decode URL-safe Base64?
Not directly, this decoder expects standard Base64. Replace - with + and _ with / first, then decode.
What is Base64 used for?
It's a way to represent binary data as plain text so it can travel through text-only systems: email attachments, data URIs in web pages, API credentials, and tokens.
Is it safe to decode Base64 from an untrusted source?
Decoding itself is safe, but treat the result like any download: don't run decoded executables or open unexpected files from sources you don't trust.

Related tools

Base64 EncoderEncode text or files to Base64 in one click. JWT DecoderRead JWT headers and payloads instantly. HTML Entity DecoderTurn HTML entities back into characters. URL DecoderTurn percent-encoded URLs back into readable text.