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ASCII85 · Adobe variant · encode · live

Encode & decode Base85

ASCII85 (the Adobe / btoa flavor) packs 4 bytes into 5 printable chars — about 25% denser than Base64. Used by PostScript, PDF streams, and Git binary patches.

Base85 / ASCII85 Converter
Input
74 B
1 lines
Output
93 B
1 lines
Status
ready
live
Ratio
1.26×
out/in
input · text
output · ascii85
9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>Cj@.4Gp$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,O<DJ+*.@<*K0@<6L(Df,
Quick Start

How to convert ASCII85

Four bytes (32 bits) become five printable characters in !..u. The z shortcut compresses all-zero 4-byte groups for extra savings.

  1. 01

    Pick mode

    Encode UTF-8 to ASCII85, or decode ASCII85 back to bytes.

    Bytes flow through TextEncoder/TextDecoder for predictable UTF-8 semantics — emoji, surrogate pairs, and combining marks all encode losslessly.

    modeUTF-8TextEncoderlosslesslive
    mode · raw bytesencode · UTF-8
    encode · decode
    loaded · UTF-8MIME · ready
  2. 02

    Paste payload

    Whitespace is tolerated in decode mode — line wraps don't matter.

    Hash and signature operations call crypto.subtle from the Web Crypto API, so output matches OpenSSL / Node bit-for-bit.

    utf8Web Cryptosubtledeterministiclive
    input · optionstext · live
    Man is distinguished…
    options applied · livelive
  3. 03

    Live convert

    All-zero groups collapse to z automatically.

    Options re-run instantly through useEffect + useMemo — switching URL-safe mode or padding doesn’t re-encode from scratch.

    livememoisedoptionsinstantreactive
    out · encodeda85 · ready
    87cURD]j
    encoded · livelossless
  4. 04

    Copy or download

    Embed straight into a PostScript or PDF stream.

    Copy uses the Async Clipboard API; downloads ship via Blob with the appropriate MIME (text/plain, image/png, …) so external tools recognise them.

    exportclipboardblobMIME-correctclient-side
    ✓ · copiedready · done
    ✓ Copied
    shipped · ready to shipsuccess
Pro tips

Encoding without surprises

Always UTF-8 first

Use TextEncoder / TextDecoder for bytes ↔ string conversion. btoa alone breaks on non-ASCII.

URL-safe vs standard Base64

Standard uses +, /, =; URL-safe swaps to -, _, no padding. Don’t mix them.

Hashes aren&rsquo;t passwords

SHA-256 is fast; that’s good for fingerprints, bad for passwords. Use bcrypt / argon2 for credentials.

Watch padding rules

Some decoders are strict about = padding, others auto-pad. If round-trips fail at exactly 1 or 2 bytes, check padding.

Use Web Crypto for keys

Generate cryptographic keys via crypto.subtle, never Math.random. The latter is predictable.

JWT decode ≠ verify

Decoding a JWT just splits and base64-decodes. Verification needs the issuer’s public key / shared secret.

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Use Cases

When to use ASCII85

PDF streams, Git binary patches, dense embedding.

PostScript / PDF

Embedded images and font data ship as ASCII85. Output round-trips losslessly with the matching decoder — both run client-side, so end-to-end testing happens in a single tab. Encoding flows through TextEncoder for predictable UTF-8 semantics.

RFC-compliant

Git binary diffs

git format-patch uses a Base85 variant for blobs. Web Crypto's subtle.digest produces output that matches OpenSSL, GPG, and Node's crypto module byte-for-byte. That makes the result trustworthy as a content fingerprint, ETag, or integrity check.

OpenSSL-matched

Configuration blobs

Tighter than Base64 when bandwidth or storage matters. Pairs cleanly with HMAC, JWT, and signed-URL workflows where bit-level correctness matters. The browser's crypto stack is FIPS 140-validated in Chrome and Firefox, so it's production-grade.

lossless

Legacy systems

btoa()-style encoding in older Unix utilities. Output uses canonical RFC 4648 / 7515 alphabets so curl, openssl, and any standards-compliant decoder accept it as input. URL-safe variants drop padding for tokens that travel in query strings.

byte-identical

Email-safe binaries

Printable-only output survives SMTP gateways. Heavy hashing runs through useMemo so large inputs don't block typing. PBKDF2, bcrypt, and Argon2 expose configurable cost factors — tune for your threat model, not the default.

spec-grade

Anywhere Base64 fits

Drop-in replacement when ASCII85 decoders exist. Same input plus same options always yields identical bytes. That's the foundation for content-addressed storage (IPFS, Git, S3 ETags) and means the output is safe to commit to fixtures.

production-ready
FAQ

Frequently asked questions

Base64 maps 3 bytes to 4 chars (33% overhead). ASCII85 maps 4 bytes to 5 chars (25% overhead) — about 7% smaller output.
A 4-byte all-zero group encodes as a single 'z' character instead of '!!!!!', saving 4 bytes.
This tool uses the Adobe / btoa alphabet. RFC 1924 (used by Z85 / ZMQ) has a different glyph set — convert separately if needed.
No. Some Adobe streams wrap with <~ ~> — strip them before pasting.
No. ASCII85 conversion runs entirely in your browser.
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