My most recent work involved trying out LightweightM2M server on Java (Leshan) with goal of forwarding data to .NET Core 2 backend serving Angular frontend. A couple weeks prior to that I put together a small Angular application with NodeJS on backend. That pretty much touches almost all major development stacks. Full stack development effort starting with working GO language on Linux and FreeBSD. Sending IoT data over CoAP to a GO based server.