ST-LINK is a very low-cost, in-circuit debugger/programmer for the STM8 and STM32. It connects to application or evaluation boards for programming and debugging via STMicroelectronics' SWIM single-wire connection for the STM8 and via a JTAG standard connection for STM32 microcontrollers.
For the STM8 MCUs, ST-LINK is driven by ST toolset, ST Visual Develop –STVD (version 4.1.0 or later) for in-circuit debugging and ST Visual Program –STVP (version 3.1.0 or later) for in-circuit programming and IAR toolset EWSTM8 (version 1.10 or later).
For STM32 MCUs, ST-LINK is driven by the Atollic toolset, TrueSTUDIO (version 1.0 or later), IAR toolset EWARM (version 5.30 or later) and Keil toolset ARM-MDK (version 3.3 or later).