Thank you guys for valuable feedback, I'll definitely consider and use it for further improvements.

Currently I'am adapting this extension also for Firefox & Tor browsers (thank you for the tip). There are some incompatibilities with manifest file and appropriate code, but I think I can solve this soon. Also, you're right with styling the extension, I'll do something with it.

That is great point about publishing the code, I was also considering this, but I'am not sure if it is good idea at this moment. I think, that in this early stage I need to be ahead of someone who just copy the code, but I'll consider it later. It seems that Google Web Store has no straight way to place signature of the extension, but maybe there is a way... I'll do some more investigations how to solve this sensitive stuff later so as it is connected with publishing the code - at least the code is already accessible directly through inspecting the extension, but is minimized at this moment so it's quite useless. However, I understand that there is big emphasis on the trust, privacy and security so I will keep this in my mind.

Conversion rates data are being fetched from CoinGecko and cached on my backend. From there data is fetched by the extension. All the user configuration is stored on local storage. No data is sending out from the extension, except of the data from feedback form, but I think I can remove this form, because there is a way to contact me through the Google Web Store. All the network traffic is also available by inspecting the extension, which itself is not a proof, but with this the extension can gather some extra trust points :-)

If you have some other considerations, I'd be happy to be inspired by reading it. Thank you very much

I've created Bitcoin Mindset browser extension, which can convert prices of various cryptocurrencies, fiat currencies or commodities between each other, so it can come handy to anyone who is interested in crypto. Extension requires no permissions, so you can rely on no misbehavior. More information and short video about this extension is available here:

https://bitcoinmindset.org/

It would be great if you try it. And if you find it useful I would appreciate positive review in Chrome Web Store or further recommendation, thanks.