What are the best free tools for SEO analysis?

Hello friends,
I had done SEO A long time ago, I stopped doing it after a few months SEO for my website. Now I want to start SEO again.
But it seems that most things have changed. earlier things used to be done manually. But today many tools are being developed that can save a lot of time.
Please friends suggest some good tools. but tools shouldn't be a black hat SEO Art. I want to do it organically.

Does this corona virus effect lead the advertising industry towards recession in 2020?

The recent outbreak of covid-19 has impacted the advertising industry and is looking forward to a recession. According to industry experts like Moody & # 39; s, this will definitely have an impact on the market. What is your observation on this?