NSIS

32 bit + 64 bit

If you build both ia32 and x64 arch, you in any case get one installer. Appropriate arch will be installed automatically.

Custom NSIS script

Two options are available — include and script. script allows you to provide completely different NSIS script. For most cases it is not required as you need only to customise some aspects, but still use well-tested and maintained default NSIS script. So, include is recommended.

Keep in mind — if you customize NSIS script, you should always state about it in the issue reports. And don't expect that your issue will be resolved.

1. Add file build/installer.nsh.
2. Define wanted macro to customise: customHeader, customInit, customUnInit, customInstall, customUnInstall. Example:

    !macro customHeader
      !system "echo '' > ${BUILD_RESOURCES_DIR}/customHeader"
    !macroend
   
    !macro customInit
      !system "echo '' > ${BUILD_RESOURCES_DIR}/customInit"
    !macroend
   
    !macro customInstall
      !system "echo '' > ${BUILD_RESOURCES_DIR}/customInstall"
    !macroend

• BUILD_RESOURCES_DIR and PROJECT_DIR are defined.
• build is added as addincludedir (i.e. you don't need to use BUILD_RESOURCES_DIR to include files).
• File associations macro registerFileAssociations and unregisterFileAssociations are still defined.
• All other electron-builder specific flags (e.g. ONE_CLICK) are still defined.

GUID vs Application Name

Windows requires to use registry keys (e.g. INSTALL/UNINSTALL info). Squirrel.Windows simply uses application name as key. But it is not robust — Google can use key Google Chrome SxS, because it is a Google.

So, it is better to use GUID. You are not forced to explicitly specify it — name-based UUID v5 will be generated from your appId or name. It means that you should not change appId once your application in use (or name if appId was not set). Application product name (title) or description can be safely changed.

You can explicitly set guid using option nsis.guid, but it is not recommended — consider using appId.