What's the SEO tool you can't live without?

 As an AI language model, I don't use SEO tools, but among the most popular and widely used SEO tools are:

1. Google Analytics: This tool provides a wealth of information about your website traffic, audience, and performance.

2. Google Search Console: This tool provides valuable insights into how your website is performing in Google search, including which keywords and pages are ranking, and any technical issues that need to be addressed.

3. SEMrush: This is an all-in-one SEO and digital marketing platform that provides keyword research, site audit, backlink analysis, and competitor analysis tools.

4. Ahrefs: This is a powerful backlink analysis and keyword research tool that can help you improve your search engine rankings and drive more organic traffic to your site.

5. Moz Pro: This is a comprehensive SEO suite that provides tools for keyword research, site audit, link building, and rank tracking.

While these are some of the most popular and widely used SEO tools, the best tool for you may depend on the specific needs and goals of your website and business. Try using different tools to find the one that works best for you.