AppImage is a format for distributing laptop software on Linux without needing superuser permissions to install the application .  It also provides a Linux distribution-diagnostic binary software deployment for application developers ,  also called Upstream packaging. Released first in 2004 under the name klik , it was continuously developed since then, renamed in 2011 to PortableLinuxApps and 2013 to AppImage .
AppImage strives to be an application deployment system for Linux with the following objectives: simplicity, binary compatibility , distro agnosticism, no installation , no root permission , being portable , and keeping the underlying operating system untouched. 
AppImage does not install the application in the traditional Linux sense by putting its various files in the distro’s appropriated places in the file system . Instead, like its predecessors klik and portablelinuxapps , no such installation actually takes place. The AppImage file is just its compressed image; This is mounted when it runs.
It uses one file per application. Each one is self-contained: it includes all libraries the application depends on which is already part of the targeted base-system. An AppImage is an ISO 9660 file with zisofs compression containing a minimal AppDir and a tiny runtime .  An AppImage applications can be added to a live CD by adding only one file to the live CD.
AppImage files are simpler than installing an application. No extraction tools are needed, nor is it necessary to modify the operating system or user environment. Linux distributions can download it, make it executable, and run it.
AppImage ‘ s predecessor klik was designed in 2004 by Simon Peter.  The client-side software is GPL licensed. Klik integrated with web browsers on the user’s computer. Users downloaded and installed software by typing a URL beginning with
klik://. This downloaded a klik “recipe” file, which was used to generate the .cmg file. In this way, one recipe could be used to supply packages to a wide variety of platforms. With klik only eight programs could be run at once because of the limitation of mounting compressed images with the Linux kernel , unless FUSE was used. The file was remounted each time the program is run, meaning the user could remove the program by simply deleting the .cmg file. A next version, klik2 , was in development; And would natively incorporate the FUSE kernel module, but it never happened past the beta stage.  Around 2011, the klik project went dormant and the homepage went offline for some time. 
Simon Peter started a successor project named PortableLinuxApps with similar goals around that time.  The technology was adapted for instance by the “portablelinuxgames.org” repository, which provides hundreds of mostly open-source video games . 
Around 2013, the software Was renamed again from portableLinuxApps to AppImage ; The license became the MIT license . AppImage is the size and AppImageKit is a concrete open source implementation. The development happens in a GitHub repository with latest changes from 2017. 
Reception and use
Klik was in 2007 the inspiration for Alexander Larsson’s glick project, the precursor of Flatpak which was released in 2016. 
Linus Torvalds ‘ dive log Application Subsurface started to use AppImage around 2015. Subsurface’s traditional packaging Was changed to a mobile , self-contained, distro-agnostic AppImage, as binary softwaredeployment for the Linux users of the various Linux distributions turned out to be problematic .   
MuseScore started in April 2016 to use AppImage builds for Linux software flavors. 
Krita , a digital painting free and open-source software application, is also deployed using AppImage from version 3.0 in May 2016.  
DigiKam , an open source photo management application, also includes an AppImage bundle from version 5.3.0, released in November 2016. 
Network World’s Bryan Lunduke noted on March 31, 2017 positively the Linux distribution- diagnostic packaging of OpenShot with AppImage. 
- Portable application creators
- Snappy (package manager)
- Zero Install , another similar project
- ROX uses directories ( AppDirs ) as application bundles.
- Jump up^ Mobily, Tony (2006-04-07). “Free Software Magazine interview with Simon Peter” . Free Software Magazine .
- ^ Jump up to:a b Peter, Simon (2010). “AppImageKit Documentation 1.0″(pdf) . PortableLinuxApps.org. pp. 2-3 . Retrieved 2011-07-29 .
The AppImage […], Be distribution-agnostic […], Remove the need for installation […], Maintain binary compatibility [ Allow to put apps anywhere […], Do not require recompilation […], Keep base operating system untouched […]
- Jump up^ AppImage: Linux apps that run anywhereon youtube.com by Peter Simon (June 2016)
- Jump up^ “Slashdot – Point-and-klik Linux Software Installation?” . Slashdot.com .
- Jump up^ Screen capture video of Klik2on video.google.com (archived)
- Jump up^ “klik – Linux Software Download” . Archived from the originalon 2007-06-26.
- Jump up^ “Portable Games for Linux” .
- Jump up^ “AppImageKit” . Github.com .
- Jump up^ Experiments with run-timeless app bundlesby Alex Larsson (2007)
- Jump up^ Linus Torvalds (2014-08-29). “Q & A with Linus Torvalds”(video) . DebConf 2014 Portland . Debian .net. 6:28 . Retrieved 2016-05-14 .
I am involved with my other dive log app. We make binaries for Windows and OSX, we basically do not make binaries for Linux. Why? Because making binaries for Linux desktop applications is a major fucking pain in the ass.
- Jump up^ Torvalds, Linus . “This is just very cool.” . Google+ .
I finally got it all to play with the “AppImage” version of + Subsurface, and it really does seem to “just work”.
- Jump up^ Hohndel, Dirk (2015-11-25). “This is just very cool.” . Google+.
I, as the app maintainer, do not want my app bundled in a distribution anymore. Way to much pain for absolutely zero gain. Whenever I get a bug in my first question is “oh, which version of which distribution?” Which set of insane patches were applied to those libraries? “. No, Windows and Mac get this right. I control the libraries my app runs against. […] With an AppImage I can give them just that. Something that runs on their computer.
- Jump up^ Weiss, Isaac. “MuseScore 2.0.3 is released” . MuseScore.org. MuseScore . Retrieved 2016-04-05 .
- Jump up^ “Krita 3.0 Released” . Krita.org . Krita. 2016-05-31.
- Jump up^ “Krita Appimage for cats” .
- Jump up^ “digiKam 5.3.0 is published” . Www.digikam.org . Retrieved 2016-12-30 .
- Jump up^ Bryan Lunduke (Mar 31, 2017). “Linux video editor OpenShot 2.3 impresses: New tools, fast performance” . Network World . Retrieved 2017-04-02 .
Interestingly, OpenShot is distributed via appimage. Linux distributions. This is the only Linux version of Linux. I personally tested this on openSUSE Tumbleweed with great success-it should run just as easily on Debian, Fedora or others. I love this approach to distributing software directly from the developers.