Z to LZ Converter
FileFlip converts Z to LZ entirely inside your browser, using libarchive compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert a Z file to LZ?#
- Drop your Z file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to LZ and the conversion starts on its own. FileFlip downloads 1.0 MB of WebAssembly the first time and nothing after that, then runs libarchive on your own machine.
- Save the LZ file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting Z to LZ lose quality?#
No. Converting Z to LZ does not touch the files inside the archive. Each member is read out and written back byte for byte, so only the wrapper around them changes and nothing is recompressed.
Is it safe to convert Z files online?#
Yes, because nothing is uploaded. FileFlip converts Z files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What Z to LZ actually does to the file#
Converting Z to LZ runs on libarchive, downloads 1.0 MB of WebAssembly the first time and nothing after that, copies the archived files through unchanged, keeps file contents.
| Engine | libarchive |
|---|---|
| Conversion path | 2 steps: Z → the unpacked files → LZ |
| Downloaded to your browser | 1.0 MB, once, then cached by your browser |
| Quality | Lossless, contents copied unchanged |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| File contents | Kept | Carried through into the converted file. |
| File timestamps | Sometimes | Survives for some files and not others. |
| File permissions | Sometimes | Survives for some files and not others. |
Worth knowing before you start:
- the output is a PAX tar archive inside the compressor, not a single compressed stream
- every entry is extracted into memory before anything is written, so a very large archive can exhaust it
What is a Z file?#
A Z file is a single stream compressed with the LZW algorithm by the Unix compress utility, the format gzip was written specifically to replace once a patent on LZW made distributing compress a legal risk.
There's essentially no reason to create a new Z file today; gzip replaced it decades ago with better compression and no patent risk.
Convert an old Z file to GZ or XZ so modern tools that dropped compress support can actually open it.
What is an LZ file?#
An LZ file is a single stream of data compressed with lzip, an LZMA-based command-line compressor that Antonio Diaz Diaz released in 2008 as a long-term-archival alternative to gzip, bzip2 and xz.
Pick lzip when an archive needs to survive years of storage or transmission and the ability to partially recover a damaged file matters more than having a GUI tool handle it.
Convert an LZ file to gzip or zip when it needs to open on a system whose tools stop at the common formats, which is most of them.
Z to LZ questions people ask#
Is a .Z file the same as gzip?
No. A .Z file is compressed with the older Unix compress utility's LZW algorithm, not gzip's DEFLATE, and the two aren't interchangeable; a tool built to read .gz files can't decompress a .Z file.
Why was Unix compress replaced by gzip?
Unix compress used the LZW algorithm, which Sperry, later Unisys, held a patent on, and the resulting licensing risk pushed the Free Software Foundation to write gzip as a patent-free, better-compressing replacement in 1992. Compress fell out of use well before the LZW patent itself expired in 2003.
Can modern tools still open a .Z file?
Many can: gzip itself can decompress .Z files even though it can't create them, and tools like 7-Zip and The Unarchiver read the format too. Native support has thinned out over the decades, so an old .Z file that a tool won't open usually just needs a dedicated uncompress utility or a converter.
What's the difference between LZ and ZIP files?
An LZ file holds a single stream compressed with lzip, not a container of separate files like a ZIP. To pack more than one file as lzip, they need to be combined into a tar archive first and the result compressed as a .tar.lz.