Base64 encoder/decoder
Encoding
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All processing for this tool happens in your browser. Your input is not sent to a server.
About this tool
Encode text as standard Base64 or decode Base64 into UTF-8 text. Conversion updates as you type or switch modes, runs in your browser, and provides a copyable result.
Common uses
- Prepare a Base64 text value for a test request or configuration field that expects this format.
- Inspect a Base64 value known to contain UTF-8 text, including Chinese, Japanese, or emoji.
How to use it
- 1.Choose Encode for plain text or Decode for a Base64 string.
- 2.Paste the input; the result updates automatically without a Run button.
- 3.Review the output and use Copy result. This tool has no file upload or download control.
Text conversion examples
Encode hello
hello
aGVsbG8=
In Encode mode, five UTF-8 bytes become eight Base64 characters, including one padding character.
Encode Chinese text
你好
5L2g5aW9
These two characters occupy six UTF-8 bytes. The result needs no padding.
Decode back to text
5L2g5aW9
你好
Choose Decode to recover the original UTF-8 text.
Decoding problems
- If decoding fails, check for invalid characters or misplaced = padding. For example, %%% and aGVsbG8=== fail and clear the result.
- Do not paste a complete data:text/plain;base64,... URL here. Use the Data URI converter for that wrapper.
- A UTF-8 decoding error can mean the decoded bytes are binary or use another character encoding. Base64 alone does not identify the original character set.
Limits and notes
- This is a text converter, not an image or arbitrary binary-file decoder. Invalid UTF-8 bytes cause a decoding error instead of being silently replaced.
- The encoder uses standard Base64 with + and / and adds = padding when needed. There is no Base64url mode; - and _ are not accepted by this decoder.
- Empty input produces no result. Encoding preserves all spaces and line breaks, including whitespace-only text. Decoding ignores ASCII whitespace in Base64 and preserves a BOM character in the UTF-8 text.
- Decoding uses the browser’s atob: ASCII whitespace and some unpadded strings are accepted. A successful conversion is not proof of strict, canonical Base64.
Frequently asked questions
Does Base64 encrypt or protect a secret?
No. Base64 is a reversible encoding with no secret key. Anyone with the encoded value can decode it; do not use it to protect passwords or tokens.
Does this tool send my input to a server?
The conversion runs locally in the browser. The converter does not upload the text you enter.
Which related tool should I use?
Use URL encoder/decoder for percent-encoding, Data URI converter for a data: URL, Character set converter for UTF-16 bytes, or Hex encoder/decoder to inspect a text value as hexadecimal UTF-8 bytes.