Frequently Asked Questions
Common questions about the Base64 tool.
Is this tool safe? Will my data be uploaded?
Absolutely safe. All encoding and decoding happens locally in your browser. No data is ever sent to any server.
How much larger does Base64 make the data?
Base64 increases size by about 33%, because every 3 bytes of input become 4 ASCII characters. For example, a 100-byte file becomes about 136 characters.
Why does decoding fail with "Invalid Base64 string"?
Common causes: spaces or newlines in the string, use of URL-safe Base64 (- and _) instead of standard (+ and /), or missing padding characters (=). Clean up your input and try again.
How to encode a file?
Click "Select File" in the File Encoding section, choose any file, and it will be automatically encoded to Base64, shown in the output box.
Does it support Chinese and Unicode characters?
Yes. The tool converts to UTF-8 before encoding, so Chinese, Japanese, emojis, and all Unicode characters are correctly handled.