The three crossword formats you'll meet are .puz (the old binary Across Lite standard), .jpz (an XML format from Crossword Solver and Crossword Compiler) and .ipuz (an open JSON format). Use .puz when you need the widest compatibility, .jpz or .ipuz when your puzzle depends on features .puz handles poorly, such as long rebus entries or unusual numbering.
Quick comparison
| .puz | .jpz | .ipuz | |
|---|---|---|---|
| Origin | Literate Software, for Across Lite (since 1996) | Crossword Solver / Crossword Compiler ecosystem | Puzzazz; spec at ipuz.org |
| Encoding | Binary | XML | JSON (text) |
| Open spec | De facto standard, community-documented | Published by its makers | Yes, public specification |
| Rebus | Supported but limited | Not limited to 4 letters | Depends on the tool |
| Circles / shading | Circles supported | Supported | Supported by spec; tool-dependent |
| Unusual numbering, diagonal clues | Limited | Supported | Spec is flexible; tool-dependent |
| Other puzzle types | Crosswords | Crosswords | Crosswords, sudoku, word search |
| Best for | Maximum compatibility | Feature-rich online solvers | Open tooling, scripts, data |
Support always depends on the tool. A format may allow something your software doesn't read or write.
What is the .puz format?
.puz is the Across Lite format from Literate Software, a standard crossword file since 1996. Nearly every desktop solver and many constructors read it. It stores the grid, solution, clues, title and author, plus optional extras such as circled squares and a scrambled solution. See how to open a .puz file for apps by platform.
Its weak spots are rebus entries and exotic layouts. Crossword blogger coverage of the .jpz format notes that rebus entries in .jpz aren't limited to four letters, which implies the tighter limit in .puz.
What is the .jpz format?
.jpz is an XML format used by Crossword Solver and Crossword Compiler. It was created partly as an open alternative when it looked as though Across Lite's format might require paid licensing, and it supports more flexible numbering, layout and formatting than .puz: non-standard square numbering, diagonal clues and longer rebus entries.
What is the .ipuz format?
.ipuz is a JSON-based format. Its specification lives at ipuz.org, and the name is a trademark of Puzzazz, Inc. Because it is plain JSON, it is easy to generate and parse with ordinary programming tools, and it covers puzzle types beyond crosswords. GNOME Crosswords uses the ipuz format through its libipuz library, and Python libraries exist for reading and writing it.
Tool support varies. For example, the open-source XWord program lists .ipuz support as partial while fully reading .puz and .jpz.
What other crossword formats exist?
- XPF: an XML format; XWord reads it.
- Native app formats: Crossfire, Crossword Compiler and others save project files that keep construction data like word-list choices. These are meant for editing in that program, not sharing.
- PDF and images: for print only; they cannot be solved interactively.
- JSON exports: app-specific. Gridsmith's JSON is its own format for backing up and moving puzzles between browsers.
Which crossword file format should I use?
- Submitting to an editor or sharing with solvers: ask the venue. When there's no preference, .puz is the safest because nearly every tool opens it. For the NYT, follow their current submission guidelines; see the NYT submission guide.
- Rebus, unusual numbering, diagonal entries: prefer .jpz or .ipuz if the receiving tool reads it.
- Backup: keep a native or JSON copy; it preserves everything the editor knows.
- Scripting or data work: .ipuz, because it is plain JSON.
What does Gridsmith read and write?
- JSON: free. Export and import any puzzle to back it up or move it between browsers.
- .puz (Across Lite): import and export with Gridsmith Plus ($4.99/month or $39.96/year).
- Print/PDF: Gridsmith Plus.
Gridsmith doesn't currently offer .ipuz or .jpz. Grids are 15×15 or 21×21 and don't support rebus, so a .puz export from Gridsmith doesn't need those features. If you need another format, convert from .puz with a tool such as XWord. Learn what makes a valid grid in crossword grid rules.
Frequently asked questions
What is the difference between .puz and .ipuz?
.puz is a binary format from Across Lite, widely supported but limited for rebus and layout. .ipuz is an open, JSON-based format with a public spec at ipuz.org.
What is a .jpz file?
An XML crossword format used by Crossword Solver and Crossword Compiler. It handles features that .puz struggles with, such as long rebus entries and non-standard numbering.
Can I convert .puz to .ipuz or .jpz?
Yes, with a tool that reads one and writes the other. Check that your converter keeps clues, circles and any rebus squares; test with a copy first.
Which crossword format has the best software support?
.puz. Nearly every desktop solver and many constructors read it.
Does Gridsmith support .ipuz?
No. Gridsmith exports JSON for free and .puz with Gridsmith Plus.