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Base64 Decoder

Decode Base64 strings back to plain text online. Handles standard Base64 and UTF-8 encoded content. Free, fast, client-side.

Your data never leaves your browser

How to Use

  1. 1

    Paste Base64 text

    Enter or paste the Base64 string you want to decode into the input field.

  2. 2

    Click Decode

    The tool converts the Base64 string back to readable text instantly.

  3. 3

    Copy the result

    Click Copy to copy the decoded text to your clipboard.

What is Base64 Decoder?

Base64 decoding reverses the Base64 encoding process, converting a Base64 string back into its original text form. This Base64 decoder lets you decode Base64 to text online — paste an encoded string and see the original content instantly, entirely in your browser with no server involved.

Developers and engineers routinely encounter Base64-encoded data across many contexts: reading API response payloads, inspecting individual segments of a JWT, decoding email attachments encoded with MIME, examining PEM certificates and cryptographic keys, and extracting embedded content from data URIs. Whenever you need to convert Base64 to text quickly, this tool gives you the answer in one click.

The decoding algorithm reads the standard 64-character alphabet (A-Z, a-z, 0-9, +, /) and converts each group of 4 Base64 characters back into 3 bytes of original data. Padding characters (= or ==) indicate that the final group contained fewer than 3 bytes. This Base64 decoding tool properly handles UTF-8 encoded content, so strings containing accented characters, CJK text, or emoji will decode correctly.

All processing runs client-side in your browser using JavaScript — your data is never transmitted to any server. For the reverse operation, use our Base64 Encode tool, and to understand how JWT tokens use Base64URL encoding under the hood, try our JWT Decoder or read the guide on Base64 Encoding Explained.

FAQ

Why does decoding fail?
The most common reasons are: the string contains characters outside the Base64 alphabet, the string has incorrect padding, or the string was encoded with a different variant (like Base64URL which uses - and _ instead of + and /). Make sure your input is valid standard Base64.
Can I decode Base64URL?
This tool decodes standard Base64 (with + and /). For Base64URL strings (common in JWTs), replace - with + and _ with / before decoding, or use our JWT Decoder which handles Base64URL automatically.
What if the decoded output looks like garbage?
The original data may have been binary (an image, a file) rather than text. Base64 can encode any binary data, not just text. If the decoded result isn't readable, the original was likely a binary file.
Is my data safe?
Yes. All decoding happens entirely in your browser using JavaScript. Your Base64 data is never sent to any server.
How do I decode Base64URL (used in JWTs)?
Base64URL uses - instead of + and _ instead of /. To decode, replace these characters back to standard Base64, then decode normally. Or use our JWT Decoder which handles Base64URL automatically.
Can I decode Base64 to an image?
If the Base64 string represents an image, decoding it as text will show binary garbage. To view the image, use a data URI in your browser: paste data:image/png;base64,YOUR_STRING into the address bar. This tool decodes to text only.

Related Articles

Base64 Encoding Explained with Examples

JWT Tokens Explained: Structure, Validation, Pitfalls

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