MPLAB is a free, integrated toolset for the development of embedded applications on Microchip’s PIC and dsPIC microcontrollers. There are two different versions you can use.
Experimental version, currently on development but includes many advanced features which ease the development process.
The MPLAB X IDE is the new graphical, integrated debugging toolset for all of Microchip’s more than 800 8-bit, 16-bit and 32-bit MCUs and digital signal controllers, and memory devices. It includes a feature-rich editor, source-level debugger, project manager, software simulator, and supports Microchip’s popular hardware tools, such as the MPLAB ICD 3 in-circuit debugger, PICkit™ 3, and MPLAB PM3 programmer. Based on the open-source NetBeans platform, MPLAB X runs on Windows® OS, MAC® OS and Linux, supports many third-party tools and is compatible with many NetBeans plug-ins.
The classic IDE of Microchip which is on version 8. It is going to be stopped by the year 2013.
MPLAB Integrated Development Environment (IDE) is a free, integrated toolset for the development of embedded applications employing Microchip’s PIC® and dsPIC® Microcontrollers. MPLAB IDE runs as a 32-bit application on MS Windows®, is easy to use and includes a host of free software components for fast application development and super-charged debugging. MPLAB IDE also serves as a single, unified graphical user interface for additional Microchip and third-party software and hardware development tools. Moving between tools is a snap, and upgrading from the free software simulator to hardware debug and programming tools is done in a flash because MPLAB IDE has the same user interface for all tools.