Base85 / ASCII85 Encoder & Decoder
These are separate formats. ASCII85 encodes byte groups using ! through u and z, with optional <~ ~> delimiters. RFC 1924 maps one 128-bit IPv6 address to exactly 20 characters. Choose the format before processing.
Maximum 1,000,000 characters. No files are uploaded.
Select the exact encoding variant, then encode or decode.
A QUICK WALKTHROUGH
How to use this tool
- Choose Adobe ASCII85 for UTF-8 text/byte data, or RFC 1924 for an IPv6 address.
- Paste input and select Encode or Decode. ASCII85 output can include or omit delimiters.
- Copy the displayed result or download the encoded text or decoded bytes.
Adobe ASCII85 for byte streams
Encode text as UTF-8 bytes. Decode ignores ASCII whitespace, accepts optional <~ and ~> markers, supports the full zero-group z shorthand and valid final partial groups, and rejects invalid digits, impossible groups, or malformed delimiters. Decoded valid UTF-8 is shown as text; other bytes are shown as Base64 with a hexadecimal view and are downloaded unchanged. This is not a file-to-file converter; encoded binary input can be pasted, and decoded bytes can be saved.
RFC 1924 for one IPv6 address
Enter one IPv6 address with eight hexadecimal groups or standard :: zero compression; an embedded IPv4 tail is accepted. Decoding requires exactly 20 characters from the RFC 1924 alphabet and rejects values outside 128 bits. Output is canonical lowercase hexadecimal IPv6. RFC 1924 is an Informational memo, not an Internet Standard; this mode does not encode arbitrary text or use the ASCII85 alphabet.
Local limits
Input is capped at 1,000,000 characters and processing stays in your browser. Invalid or changed input clears previous results and disables copy/download. Encoded data is not a cryptographic protection or a compression format.
GOOD TO KNOW
Common questions
Are ASCII85 and RFC 1924 the same?
No. ASCII85 encodes byte groups; RFC 1924 represents one 128-bit IPv6 address in 20 characters. Use the matching mode.
Can it decode any file as text?
No. Decoded ASCII85 bytes are shown as text only when they are valid UTF-8. Otherwise the page shows Base64 and hex, while download preserves the original bytes.