> trust
That's exactly right. The main attractiveness of your tool comes from the "never leaves your browser", insinuating that other similar services do send your data to a server and then who-knows has access to your sensitive data. I really like that angle. But we don't know you. We can use some tools to check that nothing is transmitted today. But who knows about the future? Maybe you change your mind? Maybe once your service becomes popular you sell it for $$$ and the new owner silently pushes things to a server "totally securely, we promise"? Or is even malicious?
> anyone can see the html/javascript
Seeing minified javascript is not the same as open source. Nobody would claim that the google doc UI is "open source".
If you open source this and it turns out as great as it seems then it can make you world famous. If you keep it closed then it will probably disappear in the vast sea of similar sevices, server-based or not (since avg Joe doesn't know the difference and doesn't care). It's your choice to make.
> Though, maybe I'll add something where you can pay to get the desktop version
Ah, thanks for your honesty here. An angle describing your project in a more bad-faith way could now be that you run beta-testing of your proprietay software through this "free" service and intend to turn it into a closed pay product once the public testing has fleshed out the main issues. That's obviously something you are free to do instead of an open source product emphasizing freedom.