I contacted the creator of the Hourglass that I mentioned, and he wrote me this below:
Generally, installing applications or running executable files (.exe files) from the internet is less safe than visiting a website or running a web app inside a web browser. Although not impossible, it is much harder for a website or web app to make a change to your computer that is malicious or that unintentionally harms or slows down your computer. That is because applications running directly on your computer can do more things than web apps can do. That means that, on the one hand, applications running directly on your computer can do more good things (if they're written well, they can have more features) or, on the other hand, more bad things (if they're malicious or just poorly designed).
All of this means that if you can find a way to do what you want to do with a web app, then you should generally prefer that. If what you want to do is done better by an application that you have to download or install, you have to decide whether or not you trust that application to be safe and to be written well. I'm afraid there isn't great advice I can give you about a way you can determine this about applications in general.
In the case of Hourglass specifically --
- It's not a malicious app (though you shouldn't trust me on that, of course).
- It's open-source. You can view the code on GitHub here to make sure that the app is not malicious and to see how it works. Or you can rely on other people have looked at it.
- When it's installed, it doesn't run in the background to check for updates, etc. That means it won't slow down your computer when you're not using it. (It does check for updates, but only when you start it yourself.)
- You can use it without installing it by downloading the "portable" version. This is still less safe than using a web app, but at least it means that it doesn't make any changes to your system (like polluting your Start Menu if you don't want that).
I hope that helps.
Kind regards,
Chris Dziemborowicz