Base85 encoder.

Base85, or ASCII85, writes four bytes as five characters drawn from the 85 printable ASCII characters from ! to u, with z standing for four zero bytes. Paul Rutter's btoa program introduced the idea in 1985; Adobe adopted it in PostScript Level 2 and in PDF (the ASCII85Decode filter), which is where most of it lives today.

Four bytes are read as one 32-bit number and written as five base-85 digits, each offset by 33 to land on a printable character. The output is a quarter larger than the input, the least of the common encodings. A final group of one to three bytes is written as two to four characters; a group of four zeros is a single z.

PDF streams and PostScript files, where binary images and fonts are embedded as text; Git's binary patches, with its own alphabet; ZeroMQ's Z85 variant for keys; and anywhere the extra density over Base64 is worth the unfriendly characters.

Denser than Base64 (25% against 33%) and that is its only advantage: the alphabet has quotes, slashes and brackets, so it needs escaping in a URL, a JSON string or a shell, and there are several incompatible variants. Use it where a format asks for it; otherwise Base64.

There are several Base85s. This one is ASCII85, as PDF and PostScript write it, optionally between <~ and ~>. Git's binary patches and ZeroMQ's Z85 use the same density with different alphabets and no z shorthand, so their text won't decode here and ASCII85 won't decode there.

No. Base85 is an encoding, not encryption: it changes how bytes are written, not who can read them, and anyone can decode it with no key. Encrypt first (AES, age, a library's sealed box) when the content needs protecting, then encode the ciphertext if it has to travel as text.

Type or paste into the input and the Base85 appears as you type: "Hello" becomes 87cURDZ. Text is encoded as UTF-8 bytes, so accents and emoji come out the same as in every language's standard library. Copy the result, download it as a text file, or press Swap to decode it back.

Drop a file onto the input or choose one with the button, and its bytes are encoded directly, not as text. Any file the browser can hold in memory works; a few hundred megabytes is fine, and the result is a quarter larger.

Adobe's tools wrap ASCII85 in <~ and ~> so a reader knows where the data starts and stops; a PDF stream relies on the ~> to end. Choose the delimiters when the text is going into a PostScript or PDF file; leave them off for anything else. The decoder accepts both.

Nothing leaves your browser. The text or file is read into memory on your machine and the encoding is computed there, in plain JavaScript; the page makes no request with it. Load the page, go offline and it keeps working.

No. The Base85 encoder is free and opens without a sign-in, an account or an install.

Nothing. The Base85 encoder holds your input in the page's memory, so closing or reloading the tab clears it, and it saves nothing in this browser.

The bar has one choice: Delimiters, none or the <~ ~> that Adobe's tools write.

Base85 output is 5 characters for every 4 bytes, so a quarter longer, and the status line under the result shows the bytes in, the characters out and the percentage.

The text is encoded as UTF-8 bytes first, so accented letters, other scripts and emoji round-trip through the decoder unchanged. Each of those characters takes more than one byte, which makes the output longer than the character count suggests.

Press Swap once there is a result and the same tool becomes the Base85 decoder, with the output moved into the input. The decoder shows the original text again.

Closest to the Base85 encoder: Base85 decoder, File to Base85, Base85 to file, Base64 encoder. Each opens on its own page, free and in the browser.

The Base85 encoder is one of 32 in its group. The group's page, /tools/encoding, lists them all.

The tool is free. Its interface is built from shadcn.io's own components (Button, Input, Slider and the rest of the registry under /ui), which come in React, Vue, Svelte and Solid. Pro adds the blocks and templates for the product around it.