Lossless archiver for Windows & Linux
Archive huge folders in minutes, not hours.
MCZ (Mega Compression Zip) uses every CPU core and, if you have one, your NVIDIA GPU,
stores repeated data once and checks every byte on the way back out. Pack any number of files and folders into one .mcz file, from the desktop app, the command line, File Explorer or your AI assistant.
Free for personal use. Organisations: free 30-day evaluation, then one licence per computer. MCZ Copy, the job queue and MCP: 30-day trial, then a one-off premium key.
> mcz c D:\Backups\CitySample.mcz "D:\Projects\CitySample" profile: profile 'Default' (backup), destination D: writes 2100 MB/s, CPU compresses 3400 MB/s -> level 5, small-file blocks up to 4 MB compressed: 193614 files, 1402118 chunks (88214 duplicate, 3120 stored raw), 113740.0 MB -> 87390.0 MB in 107.02s, 32 threads summary: 193614 files in 21480 folders, 113740.0 MB -> 87390.0 MB (76.8% of the original, 23.2% saved) in 107.0 s (1063 MB/s) > mcz t D:\Backups\CitySample.mcz verified: 193614 files, 1402118 chunks (88214 duplicate, 3120 stored raw), 87390.0 MB -> 113740.0 MB in 41.36s, 32 threads
Fast on big folders
Compressing, extracting and verifying all use every core, so the drive is normally the limit. Extracting and verifying straight from a network share run as fast as the share allows. An NVIDIA GPU can help too.
Settings choose themselves
A profile measures your PC and each destination drive once, then picks the right level for a USB disk, a share or an NVMe drive.
Repeated data stored once
Copies of the same data across files and folders take up space once, which pays off on builds, assets and backups.
Verified, byte for byte
Everything is checked on extraction and by Verify. A damaged archive is reported, never silently extracted wrong.
Command line and GUI
mcz c / x / t / l for scripts and scheduled jobs; a desktop app with six tabs for everyone else.
Built into File Explorer
An MCZ menu on Windows 11's right-click menu: compress, back up, or open, extract and verify a .mcz. Drag files onto an archive to add them. Optionally browse archives like folders and open files straight from them. More
AI assistant integration
Let Claude or another MCP-capable assistant compress, extract, verify and send archives for you, with every call shown in the app. Free for 30 days, then a premium key. More
MCZ Activity
On Windows, the MCZ Activity icon in the notification area shows the MCZ jobs running, their progress and the queue in real time. On Linux, open the job queue page at http://127.0.0.1:48631/.
Folder backup
Pick a target folder and the folders to back up. Each is compressed into its own archive, named after the folder.
MCZ Copy
Share files and folders with other PCs, protected by a PIN and encrypted on the way. Get and send in a two-panel browser. Free for 30 days, then a premium key. More
Zip, 7z and self-extracting
Also save standard .zip and .7z files for people without MCZ, or a program that unpacks itself. Convert zips and 7z files to MCZ, and sign your archives so others know they came from you. Free for everyone. More
Offline licensing
Keys are verified on the computer itself. No licence server to run, no phoning home.
Licensing an enterprise takes three steps
- Collect Machine IDs. Run our PowerShell script across your PCs (GPO, Intune or remoting) to get a CSV of PC names and Machine IDs. How
- Upload and pay. Upload the CSV, check the price and pay by card through Stripe. You get a VAT invoice.
- Download your keys. You get a CSV back with one licence key per PC, ready to deploy with
mcz license <key>.