No PDF Expert is a native app on the Mac and iOS. First of all it came out of iOS where Electron doesn run. It also older than Electron. Secondly here are the frameworks inside PDF Expert binary It a long list mostly of Swift runtime. And no Electron. Forparison here the same list for Slack an Electron app on the Mac As you can see it has the Electron framework there. In fact the Electron framework in Slack takes 13MB by itself which is larger than the whole of PDF Expert which is about 95MB.