Telerik previously offered a ZIP-based distribution that required no installation at all. This is the ideal "offline" solution:
Progress Software (owner of Telerik) still maintains JustDecompile, but the free edition is no longer a priority. Most active development focuses on their commercial decompiler inside and Test Studio . The standalone free JustDecompile receives only critical updates. telerik justdecompile offline installer link
Telerik (now part of Progress) requires a free account to access their downloads. To get the most current, secure, and "clean" version of the offline installer, follow these steps: 1. The Official Telerik Account Portal (Recommended) telerik justdecompile offline installer link