Base64 Encoder / Decoder
Encode text to Base64 or decode it back.
Encoded
8 B in · 12 B out · +50% size change
How to use it
- 1Choose Encode or Decode, and optionally enable the URL-safe variant.
- 2In Encode mode, type or paste text — or switch the source to "File" to convert an upload instead.
- 3In Decode mode, paste Base64 or a full data: URI — the prefix is detected automatically.
- 4Read the result instantly, with a byte-size comparison, a swap button, and a download option for decoded files.
Supported formats & limits
Works with standard syntax — no file size limit, since everything runs in your browser.
Example
Encoding “CalcLake” (8 bytes) produces Q2FsY0xha2U= (12 characters, a typical ~33% size increase). Enable the URL-safe variant to swap + and / for characters that are safe inside a URL, or switch the source to “File” to encode an image or document instead of typed text.
How it works
Base64 encodes binary data as text using 64 printable characters. Your text (or file) is first converted to raw bytes — UTF-8-safe for text, so accents and emoji round-trip correctly — then those bytes are mapped to Base64 characters 6 bits at a time, which is why the output runs about a third longer than the input. Decoding reverses the process; pasting a full data: URI is recognized automatically, and if the original was a file, you can download the exact bytes back out instead of reading a text approximation.