The SDK file extension is related to the ShrinkIt and used for its compressed Apple II file archives.

There are 4 other file types using
the SDK file extension!

sdk icon.sdk - Roland S-550/S-50/W-30 disk image

sdk icon.sdk - Roland S-7xx series floppy disk image

empty icon.sdk - AutoSketch drawing file

empty icon.sdk - Smart Diary Suite cookbook file

Bookmark & share this page with others:

SDK file - ShrinkIt compressed Apple II file archive

What is sdk file? How to open sdk files?

File type specification:

Archive and compressed file type icon Archive and compressed file type

A ShrinkIt whole-disk archive is an .SHK file which is usually labeled ".SDK" to show that it is a Shrinked diskette. An .SDK file can archive a 3.5" diskette (both sides) or 5.25" diskette (one side). Most are archives of 5.25" DOS 3.3 diskettes produced by 8-bit ShrinkIt.

A whole-disk ShrinkIt archive retains all data bytes on a diskette, including files, Catalog/Directory sectors, empty tracks, and DOS if present. An .sdk file of a DOS 3.3 5.25" disk created by 8-bit ShrinkIt also preserves volume number-- important for some games and utilities which depend upon volume numbers to identify disks. (5.25" whole-disk archives created by GS-ShrinkIt do not preseve volume number.)

8-bit/IIe ShrinkIt can be used to fully unshrink any Apple II .SHK file _except_ .SHK files which contain files with GS/OS resource forks and .SEA files. For this reason, 8-bit ShrinkIt should not be used to unshrink .SHK file archives containing GS programs unless you know that none of the contained files has a resource fork.

GS-ShrinkIt can handle nearly all kinds of Apple II .SHK and .SDK files. It will not handle shrinked 5.25" DOS 3.3 .SDK files created by 8-bit ShrinkIt. In fact, most users automatically use 8-bit ShrinkIt to create and unshrink .SDK files of old 5.25" wares. (Balloon does not currently support whole-disk archives.)

Naturally, things are somewhat more crowded on 64K Apple II's. On these machines, the functions are separated. SHRINK creates .SHK files and UNSHRINK unshrinks them.

On a PC, the utility NuLib (v3.24) lets you view contents and unshrink most kinds of .SHK files. (There is a handy option to unshrink and convert Apple II text files to PC text format.) It will not unshrink IIgs files with resource forks.

Here is a simple one-line batch (text) file program for easily viewing the contents of .shk files you download to a PC (just double-click on the file name): c:\nulib\nulib v %1 |more

The above is for NuLib.exe located in folder c:\nulib . Save the text as nulibv.bat in c:\nulib and tell Windows to use c:\nulib\nulibv.bat as the 'application to perform action' for doing an Open. (You do this by selecting View--Options in the My Computer window and editing the file type info for .shk files.)

NuLib can also convert 5.25" .SDK files into .PO (ProDOS order) disk images which can be used by Apple II emulators. This works for .SDK files produced by 8-bit ShrinkIt but not for those produced by GS-ShrinkIt.

The unshrinking process is very speedy and the size of a compressed ShrinkIt file is, often, around half that of the original files it contains. This makes .SHK files very handy for archiving your software. And, since a ShrinkIt file also preserves filetype information of contained files, ShrinkIt has become the preferred format for uploading and storing Apple II files on the internet.

The default software associated to sdk file type:

ShrinkIt  Microsoft Windows software

Company or developer:
Andy Nicholas

ShrinkIt is archiving utility for Apple Mac computers that uses effective LZW compression algorithm.

Help how to open:

Use ShrinkIt to open *.sdk file archives.

How to convert:

As far as we know, this .sdk file type can't be converted to any other file format. This is usually the case of system, configuration, temporary, or data files containing data exclusive to only one software and used for its own purposes. Also some proprietary or closed file formats cannot be converted to more common file types in order to protect the intellectual property of the developer, which is for example the case of some DRM-protected multimedia files.

List of software applications associated to the .sdk file extension

Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open sdk file, edit sdk file, convert sdk file, view sdk file, play sdk file etc. (if exist software for corresponding action in's database).

Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is ableto perform the specified software action, such as opening, editing or converting sdk files.

  • Open sdk file
  • Create sdk file
  • Extract sdk file

Software that open sdk file - ShrinkIt compressed Apple II file archive

Programs supporting the exension sdk on the main platforms Windows, Mac, Linux or mobile. Click on the link to get more information about ShrinkIt for open sdk file action.

Microsoft Windows:

Previous file extension
SDI file extension > Archive and compressed file types

Next file extension
file extension SDN


Follow us!

Enter any file extension without dot (e.g. pdf)
Search for file extension details and associated application(s)

RSS feed