Ascii85 Encoder / Decoder

Encode or decode binary data using Adobe / btoa Ascii85 (Base85) encoding

Mode:

Input

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Output

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What is Ascii85 Encoder / Decoder

Last reviewed: April 18, 2026

Ascii85 — also called Base85 — encodes every 4 bytes of binary data as 5 printable ASCII characters, giving roughly 25% better density than Base64 while staying human-readable and email-safe.

It is the native encoding inside PDF files, Adobe PostScript streams, and the classic btoa / atob utilities. Engineers embed binary payloads into plain-text formats like JSON, XML, or log files without the overhead of Base64.

Why use it

Save bandwidth vs Base64 when embedding binaries in text.
Decode Ascii85 blobs extracted from PDF or PostScript files.
Round-trip small binaries in unit tests and fixtures.
Troubleshoot legacy btoa output from classic Unix tools.
Teach the size-density differences between Base64 and Base85.

Features

Encodes / decodes Adobe-style Ascii85 (btoa variant)
Supports 'z' shorthand for zero groups
~25% denser than Base64
Handles whitespace gracefully
Zero-upload Ascii85 pipeline, nothing touches a server

How to use Ascii85 Encoder / Decoder

Select a mode. Choose Encode or Decode in the control bar.
Paste your data. Drop plain text (for encode) or Ascii85 (for decode) into the input.
Run and copy. Click Run and copy the resulting string from the output panel.

Example (before/after)

Plain text

Man is distinguished

Ascii85

9jqo^BlbD-BleB1DJ+*+F(f,q

Common errors

Mixed '<~' delimiters

Adobe's variant wraps output in '<~...~>'. Our tool emits btoa-style (no delimiters).

Fix: Strip the angle-tilde delimiters before decoding, or paste them and re-run.

Whitespace inside encoded data

Ascii85 ignores whitespace, but invalid characters break decoding.

Fix: Ensure only printable ASCII 33–117 (and 'z' for zero-groups) appear in the input.

Expecting Base64

Ascii85 uses a different alphabet entirely.

Fix: Use the Base64 tool if your input ends in '=' padding.

FAQ

How large is Ascii85 output vs Base64?

About 25% denser — 4 bytes → 5 chars vs Base64's 3 bytes → 4 chars.

What does 'z' mean in the output?

A single 'z' represents a full 4-byte zero group — a compact shortcut Ascii85 includes by design.

Does this match PDF Ascii85?

Yes. Remove the '<~' / '~>' wrappers PDF streams sometimes carry, then paste the body.

Does it work on binary files?

This tool accepts strings. For raw binaries, base64-encode the file first, then convert to Ascii85 elsewhere.

Is my data uploaded?

No — encoding happens entirely in your browser.

Related tools

Ascii85 pairs well with Base64, basE91, and hex encoding when you're picking a transport format. You can also browse the full Encoders & Decoders category for more options.

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