Smaller archives.Every byte back.
ZJX is a desktop archiver for Linux, launching soon. Compact .zjx archives, the formats you already use, and every restore checked against the archive's own digests.
Not released yet. Leave your email and we'll send the Linux x86_64 link on launch day. Free for personal use and eligible organizations.
Measured on real data, losses included.
We packed one 342.4 MB telemetry file with the ZJX 1.29.0 engine and 14 other compressor settings, then unpacked every result and checked it byte for byte. ZJX's compact mode came out 38.1% smaller than the best of the rest, zpaq -m5.
| Compressor | Archive size | Time | |
|---|---|---|---|
| ZJX 1.29.0 compact | 4.41 MB | 208 s | |
| zpaq -m5 | 7.13 MB | 199 s | |
| zstd --ultra -22 --long=31 (tar) | 7.28 MB | 460 s | |
| brotli -q 11 (tar) | 7.35 MB | 293 s | |
| xz -9e (tar) | 7.61 MB | 350 s | |
| 7-Zip LZMA2 -mx=9 | 9.67 MB | 41 s | |
| RAR5 -m5 | 9.84 MB | 10 s |
For reference, zip -9 made a 40.2 MB archive, 9.1× larger than ZJX's.
Compact takes its time.About 208 seconds on this file in a single run; 7-Zip LZMA2 took about 41. When you're waiting, use Instant.
Instant is the default.Instant (1.29.0 ultrafast) created and verified archives 1.247× faster than single-threaded tar | zstd -1 on our development cohort, and 1.1959× faster on a held-out cohort frozen before measurement.
Where we're slower.zstd running four threads still beats Instant: ZJX ran at 0.82× its speed. Instant archives come out about the size of tar | zstd -1's. Use Smallest when size matters.
Measured with the ZJX 1.29.0 command-line engine, compact objective on one telemetry capture; your results will depend on your data. The ZJX bytes were written by the 1.28.0 executable on 2026-09-06; the 1.29.0 release gate confirmed its compact archives are byte-identical, so this is the 1.29.0 result. Times are single indicative runs, not qualified speed results. Showing 7 of 15 settings, including the strongest. Figures for the ZJX Basic app will be published from its shipped build. Read the full benchmark record
Three modes. Pick speed or size.
Every mode writes the same .zjx format, restores byte for byte, and is free. Ultra adds a fourth, Maximum.
Instant
The default. Packs in parallel, for the archives you're waiting on.
Fast
Usually close to Smallest's size in less time. On our telemetry test the 1.29.0 engine's fast mode made the same 4.41 MB archive.
Smallest
Tries several ways to pack your files and keeps the smallest complete archive. Built for storage.
Basic is free, with no catch.
Free for personal use and eligible organizations; commercial terms apply. Opening archives is free for everyone.
- Will open what you already have
- ZIP, 7z, RAR, TAR, gz, xz, bz2 and zst, including common password-protected and split archives. The exact list ships with the release.
- Every byte checked
- Each archive carries digests for every chunk, its manifest and the whole file. Restores are checked against them.
- Yours, offline
- No account, no telemetry, no license server. Your archives belong to you.
- No nags, no clock
- No trial timer, no upgrade prompts, no artificial speed or size caps.
Five editions. One format.
Archives from every edition open in the current free app. Pro, Ultra and Mythic: pay once, keep it forever, get every update. Reserve now and pay 30% less at launch.
Basic
Create and open archives. Free for personal use and eligible organizations; commercial terms apply.
Free
Pro
Lock your archives with a password.
$39
$27 founding price
Ultra
Our strongest compression, for when every megabyte counts.
$99
$69 founding price
Mythic
ZJX for companies, licensed for commercial work at any size.
$149 / seat
$104 / seat founding price
Legend
ZJX inside your product, or tuned to your data.
Talk to us
Basic, Pro and Ultra are for individuals. Mythic and Legend license ZJX to organizations. Compare editions
Questions
Is ZJX Basic really free?
Yes, with no time limit, no nags and no speed or size caps. It's free for personal use, accredited schools, nonprofits and businesses with under USD 100,000 in annual revenue. Organizations with USD 100,000 or more in annual revenue, and government bodies, need a commercial license such as Mythic or Legend to create archives. Opening archives is free for everyone.
When can I download it?
ZJX Basic for Linux is in development and not published yet. Leave your email on the download page and we'll send the link on release day. If you need the ZJX 1.29 command-line engine today, request it from the download page. It's licensed under PolyForm Noncommercial 1.0.0; business use needs a separate written license.
Can other people open my .zjx files?
Yes. Anyone can open, list and test .zjx archives with the latest free app, including archives made with paid editions.
Do I need an account or an internet connection?
No. ZJX works offline with no account, no telemetry and no activation server. Paid license keys are checked on your machine, and ZJX never sends your files or usage anywhere.
What does one-time pricing mean?
You pay once and keep your license forever, including every update we release. When we improve compression, every edition gets better.
Pro or Ultra?
Pro adds encrypted archives. Ultra adds everything in Pro, plus Maximum mode, our private max-ratio engine, and early access to new releases. Both are one-time purchases with every update included.
What if I change my mind?
Pro, Ultra and Mythic have a 30-day money-back guarantee. Reserving costs nothing.
Which platforms are supported?
Linux on x86_64 comes first. Windows and macOS are planned; tell us which you need on the download page and we'll email you when it's ready.
Get ZJX Basic on launch day.
Free, offline and yours to keep. Leave your email and the Linux download link arrives the day it ships.