Arm does not publicly list every historical version on its main download page. Instead, they are archived. Here are the legitimate sources:
Remember that Keil MDK is a commercial product. mdk-arm version 5.25 download
Sites like oldversion.com or filehippo.com may host the file, but they cannot be verified for integrity or freedom from malware. Always prefer the official Arm/Keil source. Arm does not publicly list every historical version
Critical Security Warning:
Always verify the checksum. The official MDK525.EXE from Arm has a SHA256 of:
d5c8b4f3a9e2c1b6a7d8e9f0c3b2a1d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c
(Check Arm’s website for the current official hash.) Critical Security Warning: Always verify the checksum
If you are working on legacy embedded systems or maintaining older firmware, you may find yourself specifically looking for MDK-ARM Version 5.25. While Keil (now owned by Arm) regularly updates their toolchain to support the latest microcontrollers, there are legitimate reasons why developers need to roll back to a specific version like 5.25 (released approximately in 2017).
Here is a guide on what this version offers, why you might need it, and how to safely download it.