When comparing Eclipse Che vs Codiad, the Slant community recommends Eclipse Che for most people. In the question“What are the best cloud IDEs?” Eclipse Che is ranked 8th while Codiad is ranked 21st. The most important reason people chose Eclipse Che is:
Built-in terminal with root access so you can make changes to your running machines. Being able to SSH into the workspace so you can use a desktop IDE is handy.
Specs
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Pros

Pro SSH + terminal
Built-in terminal with root access so you can make changes to your running machines. Being able to SSH into the workspace so you can use a desktop IDE is handy.

Pro Custom commands
You can package up custom commands with your workspace and then use them (or share them) with everyone else.

Pro Docker runtimes
You can choose from pre-configured environments for Java, Javascript, C++, PHP, C#, etc., or you can define your own by dropping in a Dockerfile - makes it easy for simple and complex projects.
Pro GIT and SVN VCS support
Projects can be easily imported from any Git or Svn repository hosting service.
Pro Reproducible environment

Pro Portable workspaces
The workspace in Che includes project sources, IDE and the runtime. So if you hand your Che workspace definition to another user and they execute it they will get everything they need to build, run and debug the project.
Also the runtime is in a Docker container so it will work even if the second user is on a different OS than the original user who shared their workspace with them.

Pro Previews
Che does a nice job to automatically map the service:port running in the Docker container (e.g. tomcat on 8080) to the Docker port it actually uses (something in the ephemeral range). You never need to figure that out - it's just made available when you run your server.
Pro Merge tool for VCS

Pro Open-source
Pro Open source
You can run Codiad on your server to allow you and your team to edit files.
Simplest to run may be using a Docker image like linuxserver/codiad.
Pro Easy to self-host: Only requires PHP
It only requires PHP 5+ and Nginx or Apache. No database is required. This makes it really easy to install on many servers include shared hosting.
Pro Multi-line edit
Allows to edit multiple things are once by having multiple cursors like Sublime Text.
Pro Has many easily installable plugins
Many plugins exist, from Terminal, Git to Collaboration and Emmet... Plugins can be installed by using the web interface, or by manually extracting files to the right directory.
Pro Simple and easily managable GUI
Cons
Con Slow runtime
Online IDE is much slower than desktop one.
Con Terminal runs as same user for everyone
No matter who is the logged in user, the Terminal plugin runs commands as the PHP user. This also affects the Git plugin in that there is a single SSH key for all users using your Codiad instance.
Con Full of small bugs
There are plenty of various issues and bug that may either be due to your setup and the UI will not report them, or due to bugs in the code; I'm including common plugins here as well (just naming a few: search files and in files may report nothing if it had an error, commands stderr not printed, marketplace not showing items, search in market place showing no results, Git escaping (
by \(
in the commit message for no good reason...). Those are generally small but together it makes the product feel flawed.
Con Currently no search and replace in multiple files
There is a search in multiple files, and search & replace in current file, but not something to perform a search & replace in multiple files.
Con Terminal doesn't TTY
The terminal plugin for Codiad allows users to type some commands and see the outputs, but not interactive input is supported (i.e. stdin is closed). Meaning you cannot run Vim, Tmux or anything requiring user inputs.
Con Demo only lasts 30min
