Base64 Encoder / Decoder
Encode UTF-8 text to Base64 or decode Base64 back to UTF-8 text.
- Runs locally in your browser
- No upload required
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Supported formats
Privacy
Runs entirely in your browser. Your input is never uploaded, stored, or sent to a third party.
Encoded 5 character(s) of UTF-8 text to Base64.
How it works
- Read the input as UTF-8 bytes.
- Applied the Base64 alphabet (A-Z, a-z, 0-9, +, /) with '=' padding.
- Produced 8 character(s) of output.
- Base64 is an encoding, not encryption; it provides no confidentiality.
Methodology
- Encode by grouping input bytes in threes and mapping each group to four characters from the standard Base64 alphabet, padding the final group.
- Decode by reversing that mapping and rejecting input whose length or alphabet is not valid Base64.
- Treat the result as an encoding only: it provides no confidentiality.
Usage
- Choose encode or decode.
- Paste the text or Base64 value.
- Read the converted output.
Examples
These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.
Encode ASCII
{
"mode": "encode",
"value": "hello"
}Round-trip Unicode
{
"mode": "encode",
"value": "héllo 🌍"
}Decode
{
"mode": "decode",
"value": "aMOpbGxvIPCfjI0="
}Limitations
Where Base64 is appropriate
Base64 is for carrying binary data through channels that expect text, such as JSON fields or data URLs. It is deliberately not for hiding information: the alphabet is public and anyone can decode it.
Frequently asked questions
- Why does the encoded length grow?
- Base64 represents every three bytes as four characters, so the encoded form is about one third larger.
- Is URL-safe Base64 supported?
- This tool uses the standard alphabet. Replace '+' with '-' and '/' with '_' for URL-safe variants after encoding.
Sources
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