What is ZJX, and what files is it for?
A Linux archiver from Greyforge Labs that makes logs, telemetry, JSONL and NDJSON exports, and repeated engineering artifacts smaller, then restores them exactly. It handles files, directory trees, and safe symbolic links, and it works alongside your backup and storage systems. Product overview
How do I get ZJX, and where does it run?
ZJX Basic 1.0 is available for x86-64 Ubuntu 24.04 GNOME on Wayland or X11, and Omarchy on Hyprland. Download Basic and follow the installation instructions. For the standalone engine, ZJX 1.30.0 is the current engine release. Against 1.29.7 it writes smaller archives in every compact and fast measurement, packs 1.5x to 4.1x faster in those objectives, and restores fast and ultrafast archives faster on all five public corpora, with the same archive format as the 1.29 line. The line began when ZJX 1.29.0 was released on 2026-09-08. The command-line engine runs on x86-64 Linux with glibc; request the package from Greyforge Labs. Availability and access
Which engine mode should I choose: compact, fast, or ultrafast?
Compact when size matters: the smallest archives. Fast when balance matters: about 63.6% less creation time than compact in the 1.25.1 qualification, with no measured size penalty. Ultrafast when wall time matters: four workers pack and verify in parallel for the shortest wall time. In ZJX Basic the same choice is the smallest, fast and ultrafast mode. The mode changes how an archive is built, never what it restores. Choosing a mode
How fast is ultrafast?
Measured as verified creation (create, then independently verify), 1.29.0 ultrafast with four workers ran 1.247x faster than default tar | zstd -1 on the development cohort (95% [1.223, 1.267], Bonferroni-adjusted lower bound 1.221) and 1.1959x faster on a held-out cohort frozen before measurement (95% [1.1867, 1.2043]). Each campaign is reported on its own. Peak memory is about 71 MB. Both campaigns in full
What does the public benchmark show?
On the public http_logs-181998 corpus (363,512,754 bytes of web-server access logs), ZJX Basic 1.0.3 wrote the smallest archive of all 15 settings measured: 12,158,244 bytes, 18.6% smaller than xz -9e. Its fast mode compressed 2.4x faster than xz -9e. Every archive was restored and checked byte-for-byte by SHA-256. Anyone can download the build and rerun it. GreyforgeLabs/zjx-benchmarks
What is the 38.1% result in the release notes?
On a real 342,409,609-byte service telemetry capture, ZJX compact wrote a 4,412,984-byte archive. zpaq -m5, the strongest of 14 comparator configurations, wrote 7,125,674 bytes. Every archive was restored and hash-matched. The bytes come from 1.28.0 and are byte-identical in 1.29.0. A commercial evaluation measures your own data. Every configuration
Does the archive walkthrough run ZJX in my browser?
No. It replays one recorded run of the released 1.28.0 package over a small synthetic project. Nothing is uploaded and nothing is computed in the browser. Interactive archive walkthrough
How does the commercial evaluation work?
Tell us what you retain and what it costs. We agree scope and data handling, then run compact, fast, and ultrafast on a representative sample against your current method and the same 14-configuration comparator set, in your environment or on a controlled Greyforge host. You get archive bytes, creation and verification time, restore evidence, and resource cost. Evaluations are scoped, paid engagements. Commercial evaluation
Where does an evaluation run, and what data must I share?
A description and a reply address are enough to start. Location, access, sanitization, retention, and deletion are agreed in writing before any file moves, and the run can stay inside your environment. Hold confidential files until then. Evaluation contact
How is ZJX licensed, and what does it cost?
Free for personal use, accredited education, qualifying nonprofits and eligible organizations below USD 100,000 in consolidated annual revenue. Opening, listing, testing and extracting ZJX archives is free for everyone. See the Basic license. The standalone engine is licensed under the PolyForm Noncommercial License 1.0.0. Business use, including evaluation, deployment, embedding, hosting, and internal use, needs a separate written commercial license from Greyforge Labs; fee, support, and compatibility terms are agreed first. Desktop edition information is at ZJX.app. License and terms
What does lossless mean, and which metadata is preserved?
The original contents come back exactly. Under the exact profile, 1.30.0 also restores the directory tree, permission bits (including a literal 0000), nanosecond modification times, and relative symbolic links that stay inside the archive. Attributes ZJX cannot carry are refused, never silently dropped: setuid, setgid, sticky bits, ACLs, capabilities, and other extended attributes stop creation unless you accept their loss. Hard links become independent files, and owners and groups are not stored. Fidelity contract
Can I restore archives in ten years?
Yes. The Linux package holds everything a restore needs: no network, account, license server, or toolchain. Inspection reports which decoders an archive needs before extraction. A 1.30.0 reader restores plaintext archives from every release since 1.23 and encrypted archives from 1.27; and 1.29.7 restored every 1.30.0 archive in the release measurements. Keep the package and its checksums with your records. Offline use
How do resource limits and worker counts work?
Memory, temporary-disk, and entry-count ceilings are checked before work starts; a request over budget is refused, never run half-way. Ultrafast creation admits about 65 MiB with the default settings and four workers and testing admits about 48 MiB with the default settings (96 MiB at the maximum setting). Worker counts from 1 to 8 mean exactly that, requests above eight are refused, and the archive bytes are identical at every count. Limits and automation
What changed across releases?
1.21 STREAMWALL bounded resource use. 1.23 BLACKWIRE built the native product path. 1.25.1 NIGHTMARKET added the Compact/Fast choice. 1.26 RELICWIRE cut compact creation time. 1.27 CIPHERGLASS added password protection. 1.28 LOCKWIRE completed the workflow and package. 1.29 REDLINE added ultrafast, qualified on two cohorts. Only releases that pass every qualification gate ship. Release history
More detail in the Specs: documentation, benchmarks, releases, public records. Also: ZJX at Greyforge.