Base64 Converter
A tool for encoding text into Base64 or decoding a Base64 string back into text. All processing happens in your browser, and no data is ever sent to a server.
How to use
- Choose "Encode" or "Decode".
- For encoding, paste the text you want to convert; for decoding, paste a Base64 string.
- The result appears instantly below. "Swap result into the input" lets you feed the output straight into the opposite conversion.
- Use "Copy to clipboard" to copy the result, or "Clear" to reset the input.
About this tool
The Base64 converter lets you encode text into Base64 or decode a Base64 string back into text. It's useful for inspecting and converting Base64-encoded data found in email attachments, API responses, or configuration files.
It supports multi-byte characters such as Japanese, converting through a UTF-8 byte sequence via TextEncoder/TextDecoder, so strings containing emoji or Japanese text are encoded and decoded correctly.
Encoding “Hello” produces “SGVsbG8=”. Use the swap action to put that result into the input and decode it back to “Hello”. Copy the trailing “=” too when checking a round trip for a text field from an API.
Base64 is a reversible representation, rather than encryption. This tool displays decoded bytes as UTF-8 text, so pasting encoded image or ZIP data does not provide a way to save the original binary file.
Frequently asked questions
Can I encode strings that contain Japanese or emoji?
Yes. Your input is converted to a UTF-8 byte sequence before Base64 encoding, so text containing Japanese or emoji is handled correctly.
Why do I get an error when decoding?
An error appears when the input isn't valid Base64 (it contains disallowed characters, has an invalid length, etc.). Check for extra or missing characters and Base64URL symbols. Ordinary ASCII whitespace is ignored.
Does it support URL-safe Base64 (Base64URL)?
Currently only standard Base64 (using + and /) is supported. For Base64URL strings (using - and _), convert them to the standard format before entering them.
Is my input data sent to a server?
No. Encoding and decoding are done entirely with JavaScript in your browser.