STMicroelectronics' STM32 family of 32-bit ARM Cortex-M core-based microcontrollers is supported by a wide range of software integrated development environments (IDEs) with C, C++, Pascal and JAVA support and debugggers from major 3rd-parties (free versions are available) that are complemented by tools from ST allowing to configure and initialize the MCU or monitor its behavior in run time.
Emprog ThunderBench, fully integrated and well-crafted development C/C++ tools for ARM Cortex
IAR Integrated development environment and optimizing C/C++ compiler for ARM Cortex-M
iSYSTEM's integrated development environment (IDE) supporting its range of iTAG Debuggers for Cortex-M microcontrollers.
Raisonance branded integrated development environment for STM32 MCUs
System Workbench for STM32: free IDE on Windows, Linux and OS X
Compilers for ARM
mikroC PRO for ARM, mikroBasic PRO for ARM and mikroPascal PRO for ARM are fully-featured compilers for ARM® Cortex®-M0, M0+, M3, M4, and M7 microcontrollers.
iSYSTEM's complete software development and test solution for the STM32 MCUs
Altium's C/C++ compiler and debugger tools for ARM based MCUs
MDK-ARM software development environment for Cortex-M based MCUs
Cosmic ARM/Cortex "M" Cross Development Tools for STM32 Microcontroller
SEGGER Embedded Studio
Cross-platform Integrated Development Environment (IDE) for managing, building, testing, and deploying embedded applications
CooCox CoIDE, a free and highly-integrated software development environment for ARM Cortex MCUs
Rowley Associates CrossWorks, integrated development environment with JTAG Flash download and debug
ARM Development Studio 5 (DS-5) provides best-in-class tools for the broadest range of ARM processor-based platforms
A powerful eclipse based C/C++ integrated development tool for your STM32 projects
GreenHills integrated development and debug environment for embedded applications using C and C++