Base64 Encoder / Decoder

How it works

Base64 maps every 3 bytes (24 bits) to 4 characters from a 64-character alphabet, so encoded data is about 33% larger. When the input length isn’t a multiple of 3, = padding fills the last group.

• Text is encoded as UTF-8 first, so é (bytes c3 a9) becomes w6k=.
• Hex bytes mode encodes raw bytes, which is handy for firmware blobs, keys and register dumps.
• url-safe (base64url, RFC 4648 §5) swaps +/ for -_ and drops padding, as used in JWTs and URLs.

Decoding accepts both alphabets, with or without padding and whitespace. If the decoded bytes aren’t valid UTF-8, the tool shows them as hex instead of garbled text.

Privacy

Everything runs in your browser; nothing is uploaded. The input is remembered in this browser only, and only short inputs go into the shareable URL.

References

• RFC 4648 — The Base16, Base32, and Base64 Data Encodings