Base64 Encoder/Decoder

Input Text:

Output:

RFC 4648 Base64: output is ~33% larger than input (4 chars per 3 bytes). All processing is client-side.

Accurate Client-Side Base64 Encoding & Decoding

For security researchers and full-stack developers who need to accurately encode or decode Base64 data, this client-side tool provides a reliable solution. It strictly adheres to RFC 4648, ensuring compatibility and correctness for various applications.

Unlike server-side alternatives, this tool performs all conversions directly within your browser. This means your sensitive data never leaves your device, providing an enhanced layer of privacy and security. Whether you're working with API keys, image data, or other binary representations, you can trust that your information remains local.

Remember that Base64 encoding inherently increases the size of your data. As per RFC 4648, the output is approximately 33% larger than the original input (specifically, 4 Base64 characters are generated for every 3 bytes of input), a crucial detail for bandwidth and storage considerations.

How to Use This Base64 Encoder/Decoder

Paste or type your text into the input area.
Select either “Encode” or “Decode” from the mode dropdown, depending on your desired operation.
Click the “Convert” button to process your input.
Review the result in the output box. If you need to use the output elsewhere, click the "Copy to Clipboard" button.
For critical applications, consider verifying the output against an external reference or specification.

FAQ

Q: How does this tool handle UTF‑8 characters?

A: It first UTF‑8‑encodes the string before Base64 encoding, so all non‑ASCII characters are correctly represented.

Q: What if I paste invalid Base64 into the decoder?

A: The tool will display an error message indicating the position of the first invalid character.

Q: Does Base64 really increase size?

A: Yes, per RFC 4648 a Base64 output is about 33 % larger than the input (4 chars per 3 bytes).

Q: Is any data sent to a server when converting?

A: No, all encoding and decoding happen entirely in the browser, keeping your data local.