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Pro Access to a wide variety of Eclipse plugins
Eclipse has a huge community developing plugins that can then be found on the marketplace.
Pro A plethora of configuration options
Each component of Eclipse can be configured separately offering fine grained control.
Pro Free, cross-platform
PDT is available for free on Windows, OSX and Linux.
Pro Syntax highlighting
Eclipse PHP Development Tools (PDT) has such good syntax highlighting for PHP, CSS, HTML.
Pro Modular architecture offers flexibility in setup
Since Eclipse is highly modular by design, relying heavily on plugins for functionality it can be set up so that it includes only the necessary functionality and nothing else.
Pro Syntax validation
You would not be regret for having PDT as you IDE choices for PHP Development. It will help you validate your PHP code without you worry it will be wrong.
Con You need big memory of RAM
You need at least 4GB Ram for get the fastest PDT if you plan to use it as your PHP tools.
Con Configuring Eclipse is time-consuming
Setting up Eclipse can be difficult. Each section and each plugin of Eclipse has its own preferences that together add up to lots of tweaking.