Base64 is the encoding everyone knows, but it isn’t the most space-efficient option — ASCII85, quietly used inside every PDF and PostScript file you’ve ever printed, packs the same binary data into roughly 20% less text.
What Is the ASCII85 Encoder/Decoder?
A tool that converts text or binary data to and from ASCII85 (also called Base85), the encoding Adobe adopted for embedding binary data like images and fonts as plain text inside PostScript and PDF files.
How to Use It
- Open the tool at /tools/ascii85-encoder.
- Choose Encode or Decode mode.
- Paste your input text (or ASCII85-encoded string) into the input box.
- Read the result instantly in the output box.
Key Features
- Higher density than Base64, encoding 4 bytes into 5 characters (25% overhead) instead of Base64’s 3-into-4 (33% overhead).
- The “z” zero-run shortcut, compressing runs of four zero bytes into a single character, common in sparse binary/image data.
- Round-trip accurate, verified against the canonical Ascii85 test vector used across encoding references.
- Fully client-side, nothing you paste is ever sent anywhere.
When to Use This Tool
- Working with PostScript or PDF internals, decoding embedded ASCII85-encoded binary streams.
- Reading Git binary patches, which use a base85 variant when you run
git diff --binary. - Comparing encoding efficiency, seeing how much smaller ASCII85 output is versus the equivalent Base64 string.
Try It Now
Open ASCII85 Encoder/Decoder directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Encoding & Decoding collection on WebdevToolbox — free, browser-based developer tools with no login required.