Guide – Yosh

Compress
Add to an archive
Look inside and extract
Speed and size
Windows 11
Command line
Good to know

Compress

Right-click any file or folder and choose Yosh it! You can also select several items, or press Ctrl+A to select everything, and do the same. Files and folders can be mixed, and any number works. You always get one archive.

You select You get

One file, report.docx report.docx.yosh next to it

One folder, Holiday Holiday.yosh next to the folder

Several items An archive named after the folder they are in, saved in that folder

You select	You get
One file, `report.docx`	`report.docx.yosh` next to it
One folder, `Holiday`	`Holiday.yosh` next to the folder
Several items	An archive named after the folder they are in, saved in that folder

Yosh never overwrites anything. If the name exists you get Holiday (2).yosh.

Other ways in: right-click, Send to, Yosh it! (works for any selection), or drop files on the Yosh window from the Start menu.

Hold Shift while you right-click for two more choices: maximum (smallest files, slow) and fast (much quicker, bigger files).

Add to an archive

Drag files or folders onto a .yosh file in Explorer and they are added to it. In the viewer, drop them on the window or press Add files; they go into the folder you are looking at.

The archive is rebuilt safely: the old one stays untouched until the new one is complete, the data already inside is not recompressed, and nothing in it is overwritten. A name that exists gets a number, as in notes (2).txt.

Look inside and extract

Double-click a .yosh file to open the viewer. Browse the folders, then choose:

Extract all unpacks next to the archive, in a new folder if it holds several items.
Extract to lets you pick a folder. Select files first to extract only those.
Open opens one file straight from the archive. Programs are never run from inside an archive.
Test checks every byte against its checksum without extracting anything.

Right-click a .yosh file for Extract here, Extract to folder, and Test integrity.

Extraction never overwrites: an existing file or folder gets a number. Dates are restored, and the "downloaded from the internet" mark is carried over so Windows keeps protecting you.

Opening one file takes a while? Yosh unpacks the archive up to that file, at about 1 MB/s per core. Files stored early open quickly. One near the end of a 16 MB block can take around 15 seconds, and the rest of that block then opens instantly.

Speed and size

Balanced and Maximum use context mixing, which is how Yosh gets smaller than xz. The price is time: about 1 MB/s per core, packing or unpacking. xz packs at 2 to 5 MB/s and unpacks at over 100 MB/s.

Big jobs use every core. Inputs are cut into independent 16 MB blocks and handled at the same time, so four cores are up to four times faster on anything over 64 MB. The archive is identical whatever the number of cores.
An input under 16 MB is one block and uses one core.
Each core in use needs about 300 MB of free memory. Yosh limits itself to what is free.
Choose Fast when you only need to move something quickly: 4 to 8 MB/s, smaller than ZIP.

Measured against xz -9e on the same files, one core, same PC:

Sample	xz	Yosh	Smaller by
Python source, 4.5 MB	864 KB	709 KB	18%
C headers, 16 MB	1,723 KB	1,380 KB	20%
Documentation, 12 MB	1,876 KB	1,738 KB	7%
Program files, 20 MB	5,888 KB	5,665 KB	4%

Sample

Yosh

Smaller by

Python source, 4.5 MB

864 KB

709 KB

18%

C headers, 16 MB

1,723 KB

1,380 KB

20%

Documentation, 12 MB

1,876 KB

1,738 KB

Program files, 20 MB

5,888 KB

5,665 KB

Windows 11

Windows 11 hides classic menu entries behind Show more options. You can also press Shift+F10 on a selected file. The entries are the same. Send to, Yosh it! is always available as well.

Command line

The command-line tool is yosh.exe in the install folder (or yosh on Linux).

yosh a.txt b.txt dir/        compress into ONE archive, named like their folder
yosh file.yosh               extract
yosh l file.yosh             list the contents
yosh t file.yosh             test integrity
yosh x file.yosh -o folder   extract to a folder
yosh x file.yosh -p dir/a.txt  extract only that file or folder
yosh a file.yosh more files  add to an existing archive
yosh c folder -o name.yosh   compress to a chosen name

Options: -x maximum, -3 fast, -f overwrite, -jN use N threads (-j1 is one core).

Good to know

Yosh is lossless, and it cannot shrink data that is already compressed: video, JPEG, ZIP, encrypted files. Text, code, documents, disk images, logs and databases shrink the most.
Links and junctions are skipped, never followed. Files locked by another program are skipped and reported; the rest still goes in.
Archives made by 1.2 and later open in this version, and old 1.1 archives open too. Yosh 1.1 cannot open newer archives; it asks you to update.
Updates are cryptographically signed and checked once a day. Turn them off with "Keep Yosh up to date automatically" in the Yosh window.
Uninstall from Settings, Apps, or run Uninstall.exe in the install folder.

Stuck? See Support.

Quick guide