No IIS dependency, fast, small, simple to set up. And it uses only FOSS components to parse symbols so if you're interested you can explore everything how the index prefixes, keys etc. are parsed and built.
A couple of FOSS enthusiasts and myself have taken over the decade old game controller remapping tool DS4Windows (https://github.com/CircumSpector/DS4Windows) with the goal to rewrite major parts using latest dotnet patterns and technologies. There's still months worth of work left but despite being an ambitious task, it's quite doable and fun figuring out your way around someone else's massive code base. Join us if you like!