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Is the MDK-ARM-STM32 IDE really free/unlimited ?

Associate II

I am new to STM8/STM32 development.  At this point my interest is purely for my personal hobby (non-commercial). I was under the impression that the MDK-ARM-STM32 compiler package was a free/unlimited IDE.  

I began the process to get the package from Keil early this month, then had a death in my family and put things aside.  I can't remember how far I got .... but I've gotten emails from someone at Arm that suggest this is actually just a 5 day trial version.

Is this correct ?

Associate II

KEIL is trailed version you have to get paid version

ST Employee

Hi @DEise​ ,

Keil is free if you are using a Cortex-M0 device (STM32F0, STM32L0).

If you need a free of charge IDE, you have the TrueSTUDIO (


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Pavel A.
Evangelist III

There are basically two "free" Keil MDK variants.

One is the F0/L0 variant licensed for ST, as mentioned by Amel above.

It has flash size limit, but it is quite high (128 KB or so).

The other one is "MDK Lite" with flash size up to 32 KB. This works with all Cortex M4 and below, STM32 and other vendors.

Anything else requires paid MDK variant.

The annoying thing is that if you install "Lite" variant, it will limit flash size even for F0/L0 projects. So if you have for example F0/L0 project with size 100 KB and F4 project with size < 32 KB on one PC, you have to install two instances of MDK and enter appropriate license info for each.

Since you have WIndows (as Keil MDK works only on WIndows - there's other very attractive option

for amateur/hobbyist: Visual GDB with Microsoft Visual Studio.


-- pa