What font should I use in my blog? It's important to me to be modern but at the same tame not killing my reader's eyes.
Use FontJoy and see which ones you like.
https://fontjoy.com
Use Inter, Manrope, Sora or DM Sans. My opinion is you should go for Manrope. Sora is kind of more modern but the other three has very high readability. All of them are open source and available at Google fonts.