Developer tools
Base64 Encoder Decoder
Encode text to Base64 and decode Base64 back to text locally in your browser.
Choose Encode to turn UTF-8 text into Base64, or Decode to turn Base64 back into text. Base64 is an encoding format, not encryption. Everything runs locally in your browser; your text is not uploaded or stored.
Convert text and Base64 in both directions.
Choose Encode to turn UTF-8 text into Base64, or Decode to turn Base64 back into text. Text is encoded as UTF-8 and decoding validates the Base64 alphabet, padding, and UTF-8 output. Base64 is an encoding format, not encryption, so do not use it to protect sensitive information. Everything runs locally in your browser; your text is not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What does this Base64 encoder decoder do?
Choose Encode to turn UTF-8 text into Base64, or Decode to turn Base64 back into text. For example, the text "Hello, world!" encodes to SGVsbG8sIHdvcmxkIQ==.
How does decoding handle invalid input?
Decoding ignores whitespace, then checks that the remaining text uses only the Base64 alphabet (A-Z, a-z, 0-9, +, /) with up to two = padding characters and a length that is a multiple of four. It also verifies the decoded bytes are valid UTF-8 text, and shows a clear error when any check fails.
Is Base64 encoding secure for sensitive data?
No. Base64 is an encoding format, not encryption. Anyone can decode it, so do not use it to protect passwords, tokens, or other sensitive information.
Does my text leave my browser?
No. Encoding, decoding, and copying run locally in your browser. CodeASystem does not upload or store the text you enter.