#583 User-level (non-admin) installation option for the official NSIS installer

[Eduardo Oliveira]

Description:
Currently, running the official NSIS installer requires Administrator privileges. I would like to request that the NSIS installer be updated to support user-level (non-admin) installations, allowing developers to install and use NSIS on their machines without requiring elevated rights.

Many developers work in restricted enterprise environments or on shared machines where they do not have local Administrator privileges. Because the current NSIS installer forces a UAC elevation prompt, these developers are blocked from installing NSIS natively. While workarounds like extracting the installer using 7-Zip exist, they are unofficial, bypass the standard setup experience (like file associations and start menu shortcuts), and create unnecessary friction for new users.

Proposed Solution:
Modify the NSIS installer script to support a per-user installation mode. This could be achieved by:

• Creating a dual-mode installer that prompts the user (or automatically falls back) to install in the current user's profile (e.g., %LOCALAPPDATA%\NSIS) if admin rights are unavailable or declined.
• Setting the RequestExecutionLevel to user (or dynamically handling it) for the installer itself, writing registry keys to HKCU instead of HKLM, and creating shortcuts in the user's Start Menu.

Inno Setup:
A great example of this behavior is Inno Setup. Inno Setup allows users to install the compiler and IDE entirely within the user profile without triggering a UAC prompt (utilizing PrivilegesRequired=lowest or PrivilegesRequiredOverridesAllowed=dialog in their own script). This makes it incredibly easy for restricted users to adopt their toolset. Given that NSIS itself is used to build highly customizable installers, showcasing a dual-mode or user-level installation for NSIS's own setup would be an excellent demonstration of the engine's capabilities.

[Anders]

You can install as non-admin without 3rd-party tools:

• Run cmd.exe
• set __COMPAT_LAYER=RunAsInvoker
• nsis-setup.exe /P /S /D=%localappdata%\Programs\NSIS

but this will not successfully install shortcuts etc.

There are two reasons we don't currently support a per-user install option:

• In "Administrator Protection" mode, we need to disable the user option because it would install to the hidden admin profile. I don't think it has been documented how you detect if your token is such an admin token.
• Uninstalling. The only reliable way to know if you are uninstalling a HKCU or HKLM install is to mark the uninstaller (this is possible of course). Some versions of Windows 10 also have bugs where HKCU uninstallers are force-elevated by the settings app.