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Base85 Encoder

Encode text to ASCII85, also called Base85, or decode it back. Five ASCII characters carry four bytes, making it more compact than Base64 for binary data.

Base85

Text to encode, or ASCII85 to decode.

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How ASCII85 works

ASCII85 reads four bytes as one 32-bit number and writes it as five base-85 digits offset into the printable ASCII range starting at !. The final partial group is encoded with one extra character per byte, so no padding characters are needed. The result is about 25 percent overhead versus 33 percent for Base64.

Where ASCII85 is used

ASCII85 was designed for PostScript and PDF, where it still encodes embedded binary streams today. Git also uses a Base85 variant to encode binary patches in text form.

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Base85 Encoder FAQs

Is this the same as Z85 or RFC 1924 Base85?
No. This is Adobe ASCII85 with the ! to u alphabet. Z85 and RFC 1924 use different alphabets, so their outputs are not interchangeable with this tool.
Why is the output shorter than Base64?
ASCII85 packs 4 bytes into 5 characters while Base64 packs 3 bytes into 4 characters. For the same input, ASCII85 output is roughly 7 percent shorter.
Does it use the z shortcut for zeros?
No. A zero block is encoded as five ! characters rather than the single z abbreviation, which keeps encoding and decoding perfectly symmetrical.
Does it support Unicode text?
Yes. Input is encoded as UTF-8 bytes first, so any Unicode text round-trips correctly through encode and decode.
Is my text uploaded?
No. Encoding and decoding run entirely in your browser, so sensitive data never leaves your device.
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